MOTOR MOUTH
Here’s the problem with idle start-stop systems.
Last month, I was asked to choose which of the features in a modern car annoy me the most. Because I could, unfortunately, only pick one, I chose the infernal keyless entry system, that supposed modernization whose main effect seems to be the constant misplacement of every automotive key fob I come in contact with.
Truth be told, though, I find the modern idle startstop function much more of a nuisance. Better, for me at least, is the constant, but mild, thrum of an internal combustion engine at idle than the intermittent silence, not to mention the abrupt wake-up, of an engine that can’t decide if it’s awake or asleep. Only mildly infuriating in a fourcylinder car, it’s seriously irksome when a big V8 or a heavy-piston turbodiesel has to rumble to life at every stop sign. The only reason I didn’t choose it as my No. 1 annoyance is because, unlike keyless entry, you can always shut the bloody thing off.
Manufacturers, of course, claim such high-tech wizardry is necessary to meet increasingly stringent fuel economy regulations, start-stop only one of myriad detailed technologies — more efficient airconditioning systems, radiator shutters and other aerodynamic aids, etc. — being introduced in the quest to meet the United States’ mandate for a 54.5-mile-per-U.S.-gallon fleet average by 2025.
But does it work? More importantly, will you see any benefit?
The answer, like almost everything about fuel economy, is complicated. I went out and, trying to replicate typical city driving, tested Audi’s brand-spanking-new 2016 A6 with the start-stop function turned on and off. As unscientific as my little experiment was, I achieved about a six-per-cent fuel economy increase — 9.6 litres per 100 kilometres with the system on, and 10.2 L/100 km without — by having the engine stop at every stop sign/ street light/railway crossing I encountered. So, it works. Indeed, since my tester was an already fairly frugal 3.0-litre turbodiesel, chances are gasoline engines, especially of the larger variety, will save even more. (Edmunds.com, testing a supercharged Jaguar F-Type R, recorded a 10-per-cent increase.) That seems pretty darned impressive … Until you start doing the math.
Let’s assume your car, a typical four-cylinder gas engine family sedan, averages 10 L/100 km in the city. Let’s further assume you’ll save a realworld five per cent with an idle start-stop system by having the engine diligently extinguish itself when stopped. Plug all the numbers — $1.20 a litre for regular unleaded, 7,500 urban kilometres a year, etc. — into your smartphone calculator and it turns out you’ll save … about $50 a year.
Ouch! Not very much, eh? The number seems even less impactful when you consider that to incorporate start-stop into the modern automobile, one needs a heavier-duty starter (because of its vastly increased cycling), ditto the battery and sometimes even a second oil pump (so oil pressure builds more quickly, preventing engine and transmission damage).
Now, unless you believe automakers have suddenly become altruistic and are absorbing the cost of all this added technology, there’s a price tag to this beefing up of engine. Even factoring in a cost of $300 — a figure, by most estimates, on the low end of the upgrades — that’s at least a six-year payback, an extraordinarily long time to put up with something that can be, if you’re as sensitive as I am, a serious annoyance.
So, you might be wonder- ing, why bother? Well, the real motivation is found deep inside the 1,500 pages that are the new U.S. Corporate Average Fuel Economy standards. It turns out that, to encourage the automakers to think frugally, the regulations allow for something called “off-cycle technology credits,” essentially a reward for incorporating gadgets for which the government testers can’t measure any discernible benefit in their laboratory testing but think will be of benefit to fuel economy anyway. There’s a raft of such doodads — stopstart, various aerodynamic aids and even high-efficiency headlights are included — that garner automakers credits regardless of their benefit.
In the case of start-stop, it’s an automatic gain of 2 grams/ mile of CO2 reduction for cars, while trucks, ever advantaged by the American government, get a credit for as much as 4.4 g/mile. Throw the entire suite of accredited gadgets at a car and the benefit can be as much as 17.8 g/mile (for non-hybrid trucks), roughly equivalent to two to three miles per U.S. gallon. For an industry struggling to meet that ambitious 54.5mpg figure, it’s a freebie few automakers can turn down even if they know the benefit to consumers is questionable.
And idle stop-start is hardly the only supposedly gas-saving technology benefiting manufacturers more than consumers. I recently tested Ford’s much-ballyhooed 1.0L three-cylinder EcoBoost engine that powers the 2015 Focus SE. I then compared it with the plain Jane, naturally aspirated 2.0L four that powers the hatchback version of Ford’s compact. Surprise, surprise, at every highway speed tested, the 2.0L consumed less gas than the supposedly parsimonious 1.0L. Oh, sure, the 2.0L’s advantage was but 0.2 L/100 km, but that’s made more impressive when you consider Ford charges a whopping $1,600 extra for the 1.0L’s privilege of sucking back more gas and losing 35 horsepower.
Even in the city, where you might think those little pistons would regain their advantage (indeed, Ford rates the 1.0L as 0.8 L/100 km more frugal: 8.1 versus 8.9), the 2.0L often eked out another 0.2 L/100 km advantage. And, yes, just so you know, the teeny, tiny little EcoBoost was even equipped with idle stop-start; the 2.0L, being Ford’s bargain basement powertrain, was not.