If your car turns off at a red light, don’t panic! It’s likely equipped with a stop-start system, a fuel-saving feature now common in many vehicles. This article explains how these systems work, their potential benefits and drawbacks, and what to consider if your car has one.
How Stop-Start Systems Function
Stop-start systems automatically shut down the engine when your car comes to a complete stop, such as at a red light or in heavy traffic. Crucially, essential systems like the air conditioning, power steering, brakes, and radio remain operational, powered by the battery. As soon as you release the brake pedal and press the accelerator, the engine restarts seamlessly, allowing you to continue driving. In vehicles with manual transmissions, the system activates and deactivates based on clutch pedal engagement.
Stop-start system diagram
Fuel Efficiency and Emissions
The primary purpose of stop-start technology is to improve fuel economy and reduce emissions. By eliminating engine idling time, manufacturers claim fuel savings of 5 to 10 percent. While the actual savings may vary depending on driving conditions and individual vehicle characteristics, there’s undeniable logic in reducing fuel consumption when the car is stationary. Fewer emissions are a direct result of less fuel burned.
System Components and Reliability
To handle the frequent starting and stopping, vehicles with this technology are equipped with heavy-duty starters and larger batteries. These robust components ensure reliable operation and prevent premature wear and tear. Concerns about starter lifespan have been largely unfounded, as these systems are designed for extended use without compromising reliability.
The History of Stop-Start
While relatively new to the US market, stop-start technology has a longer history in Europe. Volkswagen introduced the first system in 1983. Mazda attempted a similar system about a decade ago without utilizing a traditional starter motor, but it proved unreliable and was never widely adopted.
Real-World Driving Experience
The driving experience with stop-start systems can vary. Some drivers find the frequent engine shutdowns and restarts jarring, particularly in heavy stop-and-go traffic. The sensation can be more pronounced in vehicles with larger engines. Conversely, smaller engines often provide a smoother transition.
Impact of High Temperatures
In hot climates, the stop-start system can impact the air conditioning’s performance. While most systems now prevent engine shutdown in extreme heat to maintain cabin comfort, older systems might struggle to keep the interior cool during prolonged stops. This is a critical factor to consider when test-driving a car in a warm climate.
Overriding the System
Most vehicles with stop-start technology allow drivers to manually disable the system via a button on the dashboard. However, this deactivation is usually temporary, resetting each time the engine is restarted. While some vehicles, especially those with sport modes, offer automatic disengagement in certain driving scenarios, remembering to turn it off each time can be inconvenient.
Is Stop-Start a Deal Breaker?
Stop-start technology, while potentially annoying to some, offers tangible benefits in fuel economy and emissions reduction. When considering a new car, be sure to test drive it and pay attention to how the system operates. Ensure it can be manually deactivated if desired. Don’t let the presence of this technology be the sole deciding factor, but factor it into your overall assessment of the vehicle.
Photo: 2022 Volkswagen Taos SE. Credit: CarPro.
