There’s an inexpensive technology that can save you about ten per cent on your fuel bill if you do mostly stop and go city driving. It’s called the Stop-Start system and carmakers are about to begin adding them to millions of new cars.

I’ve driven a number of new cars with Stop-Start and I love it. The best thing is that when you’ve got a good one you really don’t notice it at all. You hit the brake pedal and come to a stop and after a second or two the engine very quietly turns off. When you lift off the brakes you barely notice that the engine is running again. It’s smooth and quiet and seems quite normal.

It’s particularly good with hybrid cars because the electric motor turns the wheels just before the gas engine kicks in but it’s getting to be just as smooth with gas engine-only cars too. And it really does make a positive difference in fuel economy. Don’t believe anyone who tells you that it takes more gas to start a car than to just let it idle. Not true, even with modern engines that idle very slowly.

In Europe where gas and diesel cost twice as much they take fuel saving very seriously. Over there when a city bus stops to pick up passengers the engine shuts off. Makes perfect sense, doesn’t it? Why have black diesel exhaust blasting away while the bus is stationary. When the doors close and the driver’s foot comes off the brake pedal the engine starts smoothly and away they go. I’ll make that mandatory in Canadian cities just as soon as they give me the power to do so.

Tough new fuel economy standards hit the auto industry in 2016 and the car companies are using every trick in the book to get the overall fuel economy average of their entire product line down to acceptable standards. Very few cars, especially non-hybrids, have had the stop-start until now for reasons I’ll get to in a moment. But the problems are solved and the cost has come down. Ford, for example, will start offering Stop-Start in the 2013 Fusion for only three hundred bucks. If you’re a city driver you’ll save that back fast.

As I said Stop-Start has to operate so smoothly and quietly that you don’t notice it. Some of the early systems did not. Now the good ones – and I think Mazda’s is best – are seamless and imperceptible. It means you need a heavy duty starter and a stronger battery. That’s done. Plus they’re programmed to keep the engine running if the air conditioning or heating is desperately needed for the brief interval – which rarely happens.

I’ve heard people say that Stop-Start must wear out an engine faster because the oil lubrication is interrupted. But during the short time the engine is stopped the oil remains hot and retains lubrication.

If you’re looking for a new car and you do a lot of city driving you should ask if Stop-Star is available in your choices. Take a test drive to make sure it’s smooth and seamless and doesn’t bother you – and then buy it. Sometimes the simplest things make the most sense – and Stop-Start is one of them.