Jump onto any modern-car-based online forum or social media group and you’ll likely find a 'spirited discussion' on the merits of stop-start technology. Those in the 'for' camp will talk of the environmental benefits and the fuel savings.
Those in the 'against' camp will talk of the minuscule savings and the increased wear and tear on the vehicle’s electrical system.
The thing is, they’re both right.
No, we’re not fence sitting here, we’re looking at the most up to date data sets and arriving at a scientifically-backed conclusion. Stop-start is neither extremely good nor extremely bad overall. In some cases it’s a good thing, in others it’s just annoying.
Does constantly restarting cause extra wear and tear on your engine and battery?
Yep. There’s no getting around it. Specifically, your starter motor and battery. To mitigate this, manufacturers have designed batteries designed for more regular discharges and starters that are engineered more robustly, but at the end of the day you can’t argue with the physics of repeated use leading to increased wear.
Should it alarm you? Not at all but being aware of the downsides versus the convenience of all those riches you’re saving is an advantage. But even then, those savings may be less that you might have expected.
Money saved or money spent?
Back in 2015, there was a study done by Argonne national Laboratory in the US titled Stop and Restart Effects on Modern Vehicle Starting System Components. Reading and being able to quote from this study does not lead to the success one might expect on the dating scene, but it does go into incredible detail on the functionality of stop-start and whether it’s worth it or not.
Essentially, it all boils down to how often you’re turning the engine off in traffic and for how long. If you’re in dense traffic for a limited amount of time, you’re in the golden zone. If you stop between 6-8 times and the vehicle is off for more than five minutes, you’re saving money.
If you stop more often, 12-20 times per day with each off period being less than three minutes, then stop-start is actually costing you money through engine wear.
But here’s the kicker, whether it’s saving or costing you money, the amount is borderline trivial. Even if your 2.0L car is off for a mammoth nine minutes at a time, you’re only saving about $500-$600 ... a decade. At best, that’s one tank of fuel per year for a small car.
Now that may actually sound worthwhile, but again, your car has to be off for a bunch of time to achieve that. That’s best case scenario. Smaller durations of being off mean smaller savings.
At the other end of the spectrum – the worst case scenario – about 20 stop-starts a day at 60 seconds per off-period will actually cost you about $800 in increased wear and tear. Again, that’s in a ten-year period.
So, do the numbers stack up? No, not really. For either argument. If you love your stop-start, then keep it. If you hate it, get rid of it. Simple.
Assuming you’re in the ‘don’t like it’ camp, you can permanently disable the feature in a few different ways. Every vehicle is different, and some won’t allow you to permanently disable it without outside help, but in others there are often tricks like holding the button down while cycling the ignition or bridging a relay.
However, many of us are not too keen on mucking with our vehicle’s electrics, in which case you have the aftermarket to call on. First option is your local tuning workshop, who can often disable the function via their diagnostic software.
The second option is to buy an inexpensive plug-and-play module that will electronically hit the off button for you every time you start the vehicle.
Given some people legitimately get road rage whenever start-stop does its thing, it could be money well spent.
The smoothest vs. the jerkiest: Which car makers do it best?
As you might expect, the upper end of the pricing scale often reflects the quality of the start-stop function. Honda and Mazda are always reliably good, particularly in their upper end models, as are modern Range Rovers and Mercs.
Interestingly, the mid-teens Jeep Grand Cherokee is a known problem child, with a significant delay between releasing the brake pedal and the engine kicking over.
Similarly, some of the Volvo wagons are habitually ordinary and the Jaguar F-Type has earned a bit of a reputation for sounding like it’s being kicked into life by a 17-year-old trying to impress his mates.
Regardless of whether you’re a member of the love it or loathe it clubs, there’s always an option to turn it off, either for the drive or forever. And if you like it, then you’re not hurting anyone or anything by keeping it in place.
At best, it’s going to save you $60 a year. At worst, it’s going to cost you $80. And while we’re not making statements about income versus cost of living here, a great many of us spend more than that annually on coffee. You know, just for reference.
In the past 15 years as an automotive journo and 35-plus years of inveterate car-guy antics, Dex has worked across numerous titles and has even occupied the occasional editor’s chair when nobody was watching. He spends his downtime doing engine swaps (plural) on the nature strip out front and also once ripped a handbrake spin into a perfect car park. His parents remain indifferent.
