With rising fuel consumption and increasing driving costs, drivers are searching for smart solutions that reduce expenses without compromising performance. But can the ECO mode truly deliver real efficiency?

 

What Is the ECO System in Cars?

1. ECO Mode (Economical Mode) is an intelligent driving setting designed to reduce fuel consumption by electronically controlling the engine, transmission, air-conditioning system, and auxiliary components. It first appeared in the 1990s in American and German vehicles, and today it has become a standard feature in most modern cars.
2. The system’s name varies by manufacturer: ECO Assist / ECON in Honda, Active ECO in Kia and Hyundai, and Eco Pro in BMW. Despite the different names, the goal is the same — enabling the car to operate with the lowest fuel consumption possible without compromising driving safety.
3. The system relies on the PCM (Powertrain Control Module), which receives the activation command and applies precise restrictions to engine performance, such as reducing injected fuel quantity and adjusting ignition timing to achieve more efficient combustion.

 

How Does ECO Mode Work Inside the Car?

1. It reduces the amount of fuel and air entering the combustion chambers, lowering engine output and improving efficiency.
2. It decreases throttle response, making acceleration more gradual instead of sudden, which reduces fuel wasted during aggressive acceleration.
3. It adjusts transmission shift points to keep the engine at lower RPMs, reducing fuel consumption by up to 20%, depending on driving style.
4. It controls A/C compressor load and, in some vehicles, switches from AWD to 2WD to reduce energy consumption.
5. It displays real‑time driving feedback on the dashboard, such as smooth braking or gentle acceleration, helping the driver adopt a more economical driving style.

 

Does ECO Mode Actually Save Fuel?

1. Yes. Studies confirm that ECO Mode can reduce fuel consumption by 5% to 20%, with the greatest impact on straight roads and at low speeds.
2. It performs exceptionally well in city driving, where frequent stop‑and‑go traffic occurs, as it limits sudden acceleration that consumes large amounts of fuel.
3. Its effect decreases at high speeds because the car requires more power that the system cannot restrict without compromising safety.
4. Fuel savings also depend on the driver — ECO Mode is an assistant, not a substitute for economical driving habits.

 

What Are the Benefits of ECO Mode for the Driver and the Car?

1. Noticeable fuel savings, especially in daily city driving.
2. Longer engine lifespan by reducing thermal and mechanical stress caused by aggressive acceleration.
3. Lower harmful emissions, making the vehicle more environmentally friendly.
4. Improved driving behavior by encouraging a calm and balanced driving style.
5. Reduced load on auxiliary systems such as A/C and AWD, which contributes to lower fuel consumption.

 

When Should You Use ECO Mode?

1. While driving in the city or in heavy traffic at low speeds.
2. On straight roads at steady or low speeds.
3. During short trips that do not require high power or rapid acceleration.
4. When aiming to minimize fuel consumption as much as possible.
5. In moderate weather conditions that do not require maximum A/C output.

 

When Should You Avoid Using ECO Mode?

1. Highways: the car needs more power to accelerate and maintain speed.
2. Uphill driving: the engine requires higher torque, and ECO Mode may strain it.
3. Hot weather: ECO reduces A/C performance, which may weaken cooling.
4. Night driving: lighting and A/C require more power, and ECO may affect their performance.
5. Off‑road conditions: the vehicle needs strong torque for sand or rough terrain.

 

Does ECO Mode Harm the Engine?

1. It does not cause any direct damage because it operates within safe limits defined by the vehicle’s computer.
2. Problems occur only when it is used in unsuitable conditions, such as steep inclines or highways, where the engine needs more power than ECO allows.
3. The system is designed as an assistant, not a permanent mode for all situations.

 

Does ECO Mode Affect Vehicle Performance?

1. Yes, it noticeably reduces throttle response — intentionally — to achieve fuel savings.
2. It makes the car less responsive during acceleration, especially from a standstill.
3. It alters transmission behavior to be smoother and more fuel‑efficient.
4. It may reduce A/C cooling power, especially in smaller vehicles.
5. This effect is not a flaw; it is part of the system’s efficiency‑focused philosophy.

 

Can ECO Mode Be Used All the Time?

It can, but it is recommended to turn it off when more power is needed or when driving conditions are unsuitable.

 

Why Does the ECO Indicator Disappear from the Dashboard?

It disappears when the driver presses the accelerator aggressively, meaning the driving is no longer economical.

 

Does ECO Mode Affect the A/C?

Yes, it reduces cooling power to lighten the load on the engine.

 

Does ECO Mode Extend Engine Life?

Yes, because it reduces stress and heat generated during combustion.

 

Is ECO Mode Suitable for Older Cars?

The system is typically available only in modern vehicles.

 

Is ECO Mode Worth Using?

1. If you drive mainly in the city or at low speeds — yes, it provides clear fuel savings.
2. If you drive on highways or need strong performance — it’s better to turn it off.
3. ECO Mode is not magic, but it is an effective tool that helps you drive economically and achieve real fuel savings.

 

You might pay extra for higher‑octane fuel assuming it delivers better performance, only to discover that nothing changes at all. So, is choosing the correct octane rating truly what gives your engine its real power?

 

Does the octane rating affect engine performance?

1 The octane rating measures a fuel’s ability to resist premature combustion (pre‑ignition) inside the combustion chamber. It is a key factor in determining whether the fuel is compatible with the engine’s compression design. Higher octane means greater resistance to knock under high pressure. 

2 Modern high‑compression engines require higher‑octane fuel such as 95 to ensure controlled combustion, prevent knocking, and maintain smooth performance. 

3 Economy or older engines typically operate efficiently on 91 octane because they do not generate high cylinder pressure and therefore do not require strong knock resistance. 

4 Choosing the correct octane directly affects throttle response, engine smoothness, and performance stability under various conditions such as high ambient temperatures or heavy loads.

 

Does using higher‑octane fuel than recommended improve performance?

1 Using 95 octane in an engine designed for 91 does not increase power, because the engine is not engineered to benefit from higher knock resistance. 

2 Standard engines lack the sensors and ignition‑timing maps needed to adjust spark timing to take advantage of higher octane, so performance remains unchanged. 

3 In certain sports or turbocharged engines, higher octane may provide a slight improvement in responsiveness, but only if the engine can automatically advance ignition timing to utilize the extra knock resistance.

 

Does using lower‑octane fuel cause problems?

1 Using 91 octane in an engine that requires 95 leads to knocking, which is uncontrolled combustion causing vibrations inside the cylinder. 

2 Persistent knocking reduces engine power and weakens acceleration, especially when climbing hills or driving with heavy loads. 

3 Imperfect combustion increases fuel consumption because the engine compensates for power loss by injecting more fuel. 

4 Long‑term knocking can damage spark plugs, the knock sensor, or even the cylinder head in severe cases.

 

What is the main difference between 91 and 95 octane fuel?

1 The difference is not about quality or cleanliness, but about each fuel’s ability to withstand pressure inside the combustion chamber. 

2 91 octane suits low‑ to medium‑compression engines, while 95 is intended for high‑performance or turbocharged engines. 

3 Some manufacturers design engines with precise octane requirements, making adherence to the recommended fuel essential for optimal performance and engine longevity. 

4 Choosing the correct fuel type should always follow the manufacturer’s recommendations.

 

Does fuel type affect fuel consumption?

1 The correct octane helps achieve complete combustion, reducing fuel consumption and improving efficiency. 

2 Using lower octane than required leads to imperfect combustion, increasing consumption by 10–15% in some vehicles. 

3 In high‑performance engines, 95 octane may offer better efficiency at high speeds because the engine operates with ideal ignition timing and without knock. 

4 In economy cars designed for 91, you will not notice any difference in consumption between 91 and 95.

 

Does mixing 91 and 95 octane fuel harm the engine?

1 Mixing the two does not cause direct damage, as the engine can handle blended octane normally. 

2 If your car requires 95, mixing may lower the effective octane and cause mild knock under heavy load. 

3 If your car runs on 91, mixing will not provide any performance benefit. 

4 It is best not to rely on mixing as a long‑term solution; always use the correct fuel for consistent performance.

 

Does 95 octane fuel clean the engine better than 91?

1 The octane rating has no relation to the detergents or cleaning additives in the fuel. 

2 Some fuel companies add more detergents to 91 than 95, and vice versa, so octane alone is not an indicator. 

3 Engine cleanliness depends on the quality of chemical additives, not the octane rating. 

4 For engine cleaning, use fuel with certified additives or dedicated cleaning products.

 

How does fuel choice affect maintenance?

1 Using the correct octane reduces carbon buildup in the combustion chamber and prevents abnormal heat levels. 

2 Incorrect fuel can cause spark plug issues, knock sensor faults, or even cylinder head damage in severe cases. 

3 Proper fuel maintains stable engine performance and reduces the need for frequent maintenance. 

4 Following manufacturer recommendations saves you unnecessary repair costs over time.

 

What is the golden rule for choosing fuel?

1 Always follow the vehicle’s manual; recommendations are based on engine design and combustion requirements. 

2 Do not use higher octane if your car does not need it—you will gain no additional benefit. 

3 Do not use lower octane in high‑performance engines to avoid costly future damage.

 

Do modern cars need 95 octane more than older ones?

1 Many modern engines use technologies like direct injection and turbocharging, which require higher octane for controlled combustion. 

2 Older engines generally operate well on 91 due to lower compression. 

3 Some modern economy cars are still designed for 91 despite advanced technology, so generalization is not possible. 

4 Always check the vehicle manual or the fuel cap label.

 

Does climate or temperature affect fuel choice?

1 In hot climates, engines experience higher pressure, making correct octane selection more critical. 

2 Higher octane fuel handles heat better, especially in high‑performance engines. 

3 In cold climates, the difference between 91 and 95 becomes less noticeable because thermal pressure inside the engine is lower. 

4 Climate does not change the required octane; it only affects engine behavior when using an incorrect fuel type.

When a car begins to show slight vibrations while idling, the issue shifts from a minor annoyance to a warning sign. So, what causes a vehicle to shake while standing still?

 

What Are the Main Causes of Car Vibration?

Vibration at idle or during engine startup is usually linked to a malfunction in one of the engine’s core systems. The most common causes include: 

1. Worn spark plugs or ignition coils, leading to irregular combustion inside the engine.
2. Dirty throttle body or clogged air filter, disrupting the air–fuel mixture.
3. Clogged fuel filter or weak fuel pump, reducing fuel flow to the engine.
4. Damaged engine mounts, which are designed to absorb vibrations.
5. Faulty MAF sensor or oxygen sensor, causing unstable engine RPMs.

 

Do Faulty Spark Plugs Cause Vibration at Idle?

1. Worn or dirty spark plugs lead to misfires, creating noticeable vibration while idling.
2. Bad spark plugs reduce engine power and increase fuel consumption, with vibrations especially noticeable in Reverse (R) or idle mode.
3. Spark plugs should be inspected and replaced immediately when signs of weak ignition appear.

 

Do Faulty Ignition Coils Cause Engine Vibration While Idling?

1. Ignition coils generate the spark, and any malfunction results in weak or intermittent ignition.
2. Even the failure of a single coil can cause significant engine shaking, especially at idle.
3. Coils should be tested using a diagnostic scanner and replaced if defective.

 

 

Can a Clogged Air Filter Cause Vibration While the Car Is Stationary?

1. A clogged air filter reduces the amount of air entering the engine, disrupting the air–fuel ratio.
2. This imbalance leads to irregular combustion, causing vibration at idle.
3. The air filter should be cleaned or replaced regularly, especially in dusty environments.

 

Does a Clogged Fuel Filter Cause Car Vibration?

1. A blocked fuel filter restricts fuel flow, resulting in weak combustion.
2. Vibration becomes noticeable at idle due to unstable engine RPMs.
3. The fuel filter should be replaced during every scheduled maintenance.

 

Do Damaged Engine Mounts Cause Vibration at Idle?

1. Engine mounts absorb engine movement; when worn, they cause strong vibrations at idle.
2. The vibration increases during startup or when shifting to Drive (D).
3. Engine mounts must be replaced when cracks or wear appear.

 

Do Faulty Air Sensors or Throttle Body Issues Cause Vibration?

1. A faulty MAF sensor sends incorrect readings to the ECU, disrupting the air–fuel ratio.
2. A dirty throttle body or clogged injectors causes noticeable vibration at idle.
3. The throttle body and injectors should be cleaned, and the MAF sensor inspected.

 

Can ECU Problems Cause Vibration at Idle?

1. Water intrusion or software malfunction in the ECU can cause irregular engine operation.
2. Vibration becomes noticeable during startup or while idling.
3. The ECU should be inspected, reprogrammed, or repaired.

 

 

Do Fuel System Issues Cause Vibration While the Car Is Stationary?

1. A weak fuel pump or unstable fuel pressure causes fluctuating RPMs.
2. Vibration is more noticeable at idle than while driving.
3. Fuel pressure should be tested and injectors cleaned.

 

 

Can Tire or Wheel Issues Cause Vibration at Idle?

1. Although less common, damaged tires or unbalanced wheels can cause noticeable vibration even when stationary.
2. The vibration often appears in the steering wheel or cabin.
3. Tires should be balanced and inspected for defects.

 

 

Do Transmission Problems Cause Vibration at Idle?

1. A worn clutch or damaged transmission components can cause irregular power delivery.
2. You may feel vibration at idle or when shifting into Drive (D).
3. The transmission should be inspected and serviced by a specialist.

 

Tips to Prevent Engine Vibration

1. Replace spark plugs and filters on time and never delay scheduled maintenance.
2. Clean the throttle body and injectors periodically for stable combustion.
3. Inspect engine mounts when any unusual noise or vibration appears.
4. Use high‑quality fuel to prevent deposits in the injection system.
5. Monitor the check‑engine light and never ignore dashboard warnings.

  As engine issues and performance loss become increasingly common, the demand for smarter technologies that enhance cylinder breathing has grown. Variable Valve Timing raises a key question: can it truly redefine engine power and efficiency?

 

What Is the VVT System and How Does It Work Inside the Engine?

1. The Variable Valve Timing (VVT) system adjusts the timing of the intake and exhaust valves according to engine speed and load, enhancing the engine’s internal breathing efficiency.
2. The system modifies the valve opening moment, duration, and lift, allowing better airflow at high RPMs and reducing fuel consumption at low RPMs.
3. It relies on sensors such as the camshaft position sensor and crankshaft position sensor to send real‑time data to the ECU, enabling precise timing adjustments.
4. The actual adjustment is performed by the VVT solenoid, which directs oil pressure to the cam phaser to advance or retard camshaft timing.

 

How Does VVT Increase Engine Power?

1. When additional power is needed, the system advances the intake valve timing, allowing more air into the cylinders, which increases combustion and power output.
2. At high RPMs, the intake stroke duration becomes shorter; VVT improves cylinder filling, resulting in higher horsepower.
3. The system enhances low‑RPM torque by retarding the exhaust valve timing, retaining some exhaust gases inside the cylinder and reducing fuel demand.
4. The result is a more flexible engine with better acceleration and quicker throttle response.

 

What Are the Main Components of a VVT System?

1. Camshaft Position Sensor: Monitors camshaft position for accurate timing control.
2. VVT Sensor: Measures oil pressure and operating temperature, sending data to the ECU.
3. VVT Solenoid (Oil Control Valve): Regulates oil flow to the cam phaser.
4. Cam Phaser: Rotates the camshaft to alter valve timing.

 

What’s the Difference Between VVT, VVT‑i, VTEC, and VANOS?

1. VVT: The general term for variable valve timing technology.
2. VVT‑i (Toyota): An enhanced version featuring intelligent timing control.
3. VANOS (BMW): Uses oil pressure to adjust camshaft positioning.
4. VTEC (Honda): Alters both valve timing and valve lift, known for its sporty performance characteristics.

 

What Are the Benefits of a VVT System?

1. Increased horsepower at high speeds.
2. Improved torque at low RPMs.
3. Noticeable reduction in fuel consumption.
4. Lower harmful emissions.
5. Smoother engine operation with reduced vibrations.

 

What Are the Signs of a Failing VVT System?

1. Poor acceleration or loss of power.
2. Vibrations at idle or fluctuating RPM.
3. Abnormally high fuel consumption.
4. Check Engine light triggered by camshaft or VVT sensor faults.

 

What Causes VVT System Failures?

1. Low or contaminated engine oil—the most common cause.
2. Clogged VVT solenoid due to sludge or deposits.
3. Faulty VVT sensor or incorrect data transmission.
4. Wear in the cam phaser or related mechanical components.

 

How Is the VVT System Maintained?

1. Change engine oil on schedule to prevent solenoid blockage.
2. Clean or replace the VVT solenoid when performance issues appear.
3. Periodically inspect camshaft and crankshaft sensors.
4. Use engine oil that meets the manufacturer’s specifications.

 

 

Can You Drive With a Faulty VVT System?

1. Short‑distance driving is possible, but prolonged use may cause severe performance loss and increased fuel consumption.
2. In some cases, it may lead to damage to the cam phaser or camshaft.

 

Does a Faulty VVT Affect Engine Sound?

1. Yes. A failing VVT system may cause ticking, rattling, or roughness, often due to cam phaser issues or low oil pressure.

 

Is the VVT System Part of the Camshaft?

1. Yes. The cam phaser is mounted directly on the camshaft and controls its rotational angle.

 

With the increasing number of driver complaints about heavy steering and poor response accuracy, the EPS system has emerged as a modern solution that offers smoother and safer driving.  what  is this system?

What Is the Electric Power Steering (EPS) System and How Does It Work?

1. The EPS system relies on an electric motor and an Electronic Control Unit (ECU) to provide steering assistance, instead of the traditional hydraulic pump.
2. A Torque Sensor measures the force applied by the driver on the steering wheel, then sends the data to the ECU to determine the precise amount of assistance needed.
3. The system operates variably: light and easy at low speeds, firmer and more stable at high speeds, enhancing control and safety.

 

What Are the Main Components of the EPS System?

1. Electric Motor: Converts electrical energy into mechanical force to assist in turning the steering wheel.
2. Electronic Control Unit (ECU): The brain of the system, analyzing sensor data and determining the required assistance level.
3. Steering Sensors: Such as the steering angle sensor and torque sensor, responsible for reading steering wheel movement and vehicle speed.

 

What Are the Types of EPS Systems?

1. Column Assist EPS: The most common in small and mid‑size cars due to its simplicity and low cost.
2. Pinion Assist EPS: Provides better road feel and is used in sporty vehicles.
3. Dual Pinion EPS: Suitable for larger vehicles and SUVs as it can handle higher steering loads.
4. Rack Assist EPS: The most precise and powerful, used in heavy-duty or high‑performance vehicles.

 

What Are the Advantages of the EPS System?

1. Reduced fuel consumption since it does not rely on a constantly running hydraulic system.
2. Lower maintenance due to the absence of hydraulic fluid and hoses that may leak.
3. Integration with modern driving systems such as lane-keeping assist, self‑parking, and electronic stability control.
4. More precise control and faster response thanks to adaptive electronic programming.

 

What Are the Disadvantages of the EPS System?

1. Higher repair costs compared to hydraulic systems, especially when the ECU or motor fails.
2. Less road feedback in some vehicles, especially older models, although modern systems have improved significantly.
3. Full dependence on electrical power, meaning any weakness in the battery or alternator can cause steering heaviness.

 

What Are the Most Common EPS System Failures?

1. Sudden heaviness in the steering wheel accompanied by the EPS warning light, often caused by a torque sensor issue or electric motor failure.
2. Steering vibration or shudder due to mechanical faults or the need for sensor calibration.
3. Failure of the steering wheel to return to center due to software issues or ECU malfunction.
4. Buzzing or clicking noises from the steering column, which may indicate early motor wear.

 

How Is the EPS System Maintained?

1. Checking the battery and alternator, as the system is highly sensitive to voltage drops.
2. Regular inspection of electrical connections and sensors to ensure no damage or corrosion.
3. Avoiding strong impacts such as hitting curbs or potholes, which may damage sensitive sensors.
4. Avoiding holding the steering wheel at full lock (right or left) for long periods while parking.

 

How Does EPS Improve Fuel Efficiency?

1. EPS operates only when needed—when the driver turns the steering wheel—eliminating the constant energy consumption of hydraulic systems.
2. The absence of a hydraulic pump reduces engine load, lowering fuel consumption by 3–5% in some vehicles.
3. The system helps reduce carbon emissions, making it a preferred choice for manufacturers aiming to meet modern environmental standards.

 

How Does EPS Integrate with Autonomous Driving and ADAS Systems?

1. EPS relies on full electronic control, allowing seamless integration with systems such as lane‑keeping assist, self‑parking, and emergency steering.
2. The ECU can adjust the steering angle precisely without driver input—an essential feature for autonomous vehicles.
3. The system enables quick and accurate maneuvers in emergency situations, such as collision avoidance.

 

What Are the Latest Developments in EPS Technology?

1. Use of high‑efficiency BLDC motors that deliver higher torque with lower energy consumption.
2. Development of more accurate torque sensors based on advanced magnetic technologies.
3. Incorporation of AI algorithms to analyze steering data, improving road feel and predicting driver behavior.
4. Enhanced ECU software offering multiple driving modes such as Comfort, Sport, and Dynamic.

 

With crowded roads and constantly changing speeds, drivers often experience fatigue that reduces focus and increases driving risks. But can a simple system offer you greater comfort and safety on the road?

 

What Is Cruise Control in a Car?

1. Cruise Control is an electronic system that automatically controls the throttle to maintain a constant speed set by the driver without the need to keep pressing the accelerator pedal.
2. It is designed to reduce fatigue during long trips, especially on straight highways where stopping or changing speed is minimal.
3. The system relies on an Electronic Control Unit (ECU) that receives the driver’s commands and adjusts the speed with high precision.
4. It typically operates at speeds above 40 km/h, and it is not recommended for use in city traffic or congested areas.

 

How Does Cruise Control Work Inside the Vehicle?

1. When the system is activated, the car’s computer reads the current speed and maintains it automatically.
2. It uses speed sensors, the ECU, and activation buttons to regulate speed without driver intervention.
3. When going uphill, the system increases engine power to compensate for speed loss; when going downhill, it reduces acceleration to maintain the preset speed.
4. In modern systems, sensors and radars interact with traffic conditions to adjust speed automatically.

 

Types of Cruise Control in Modern Vehicles

1. Conventional Cruise Control: Maintains a fixed speed manually without monitoring vehicles ahead.
2. Adaptive Cruise Control (ACC): Uses a front radar to adjust speed based on traffic flow and maintain a safe following distance.
3. Smart Cruise Control: Capable of stopping and resuming movement automatically in traffic jams, considered a step toward autonomous driving.
4. Older Mechanical Systems: Relied on a mechanical cable to operate the throttle instead of the driver’s foot.
5. Modern Electronic Systems (Drive-by-Wire): Fully electronic, using sensors without any mechanical cables.

 

How to Use Cruise Control Properly

1. Drive until you reach the desired speed (usually above 40 km/h).
2. Press the ON or Cruise button to activate the system.
3. Press SET to lock in the current speed.
4. Use the + / - buttons to increase or decrease speed without using the pedals.
5. To pause the system, press Cancel or use the brake pedal.
6. To resume the previous speed, press RES.
7. You can override the system by pressing the accelerator; it will return to the preset speed once you release the pedal.

 

Benefits of Cruise Control While Driving

1. Reduces fatigue on long trips by relieving pressure on the foot.
2. Saves fuel by maintaining a steady speed and reducing sudden acceleration.
3. Enhances safety by preventing unintentional speeding.
4. Improves focus on the road instead of constantly monitoring speed.
5. In adaptive systems, it helps prevent rear-end collisions by maintaining a safe distance.

 

When Should You Avoid Using Cruise Control?

1. In heavy city traffic.
2. During rain, snow, or on slippery roads.
3. On mountainous or steep downhill roads.
4. When visibility is poor or in dense fog.
5. When feeling tired or unfocused.

 

Common Cruise Control Malfunctions

1. Faulty Brake Light Switch: The most common reason the system fails to activate.
2. Damaged Clock Spring: Causes malfunction of steering wheel control buttons.
3. ABS or Wheel Speed Sensor Issues: Prevent the system from reading speed accurately.
4. Blocked Front Radar in ACC systems due to dirt or rain.
5. ECU Malfunction: Less common but still possible.

 

Does Cruise Control Actually Save Fuel?

1. Yes. Engineering analysis shows that the system helps reduce fuel consumption by maintaining a steady speed and preventing repeated acceleration.
2. The benefit is greatest on long, straight highways.
3. On mountainous or winding roads, it may not be as effective.

 

Can Cruise Control Be Installed in a Car That Doesn’t Have It?

Yes, it can be installed in most vehicles, but it is recommended to have it done by a qualified technician to ensure compatibility with the car’s electronic system.

 

Does Cruise Control Harm the Engine or Transmission?

No, the system is completely safe and does not cause any damage to the engine or transmission.

 

Why Does the Car Speed Up on Downhills Even With Cruise Control On?

Because gravity increases the vehicle’s speed, and some systems—especially traditional ones—do not apply automatic braking.

Is Cruise Control Suitable for City Driving?

It is not recommended due to frequent stops and constantly changing speeds