Stop-start system in a Mazda can be switched off with the “i-stop” button.
Stop-start systems are standard in most (if not all) European cars. This feature is also becoming common in other makes, too.
If you’re a new car owner or are still learning about cars, stop-start systems might be a mystery. How exactly do they help you save petrol?
STOP-START: IT’S ALL ABOUT FUEL EFFICIENCY
The internal combustion engine is inherently inefficient, which is why carmakers and engineers have always prioritised fuel efficiency.
Electronic fuel injection, forced induction, lean-burn combustion, low-friction bearings and variable valve control are some of the essential technical ingredients that can improve fuel consumption.
Efficiency is also affected by drivetrain designs and aerodynamic considerations.
Water injection: A super-cool way to to get better fuel economy
THAT’S WHERE STOP-START COMES IN
Stop-start switches off the engine when the car comes to a standstill, say, at a traffic light junction. Some drivers find this feature annoying, but its fuel-saving effect is indisputable.
Think about it for a moment: When stationary, any motor vehicle with an internal combustion engine that’s running does exactly zero kilometre per litre of fuel.
In certain on-board computers, the displayed value changes from km/litre to litres/hour when the engine is idling.
This lets the driver know that the fuel is still flowing/combusting even though the vehicle isn’t moving.
Stop-start shuts down the engine when the car comes to a complete stop.
As soon as the brake pedal is released (or clutch pedal is depressed for a manual car), the “sleeping” engine is restarted immediately.
The stop-start system includes a dedicated control unit that monitors a variety of parameters, including the battery’s state, air-conditioning demand and even the position of the crank.
If the combination of factors is not ideal for stop-start operation, the function will not be activated.
For example, when the battery is not fully charged up yet, or if the air-con needs to stay on, the controller will not shut down the engine.
SPECIAL COMPONENTS AND BATTERIES
The starter motor, alternator and battery in a car with stop-start have been specified/ modified accordingly.
This is so that the high frequency of starts/restarts won’t reduce their life cycles. Or, require shorter service intervals compared to a car without stop-start.
The fully sealed lead-acid battery in a car with stop-start is a special one, which cannot be substituted with a regular 12-volt unit found at tyre and battery shops.
An important element in every stop-start system is the automatic/automated transmission’s ability to allow the engine to start and engage drive in less than half a second.
Stop-start alone has been proven to reduce average fuel consumption by around 8 percent, although this varies depending on the extent of urban driving.
