Car_Warmup

When It Comes to Warming Up a Cold Car Before Driving It, Fathers Don’t Always Know Best

It’s a myth that cold weather demands that you let your car idle in the driveway. Here’s why.

If the modern automobile had a status on Facebook, it would undoubtedly be “It’s complicated.” With their computer-controlled fuel-injection systems, continuously variable transmissions and three-phase four-pole AC induction motors, the days when every Tom, Dick or Harry could wrench on their ride seem long gone. So let us help — especially with the seemingly mundane stuff that if not done properly, your dad and/or his favorite mechanic vowed would ruin your car forever. Because when it comes to cars — and this column — no question is too dumb.

To this day my dad, who lives in Chicago, argues that you have to warm your car up before you drive it in the winter. I, on the other hand, argue that in 2020, it doesn’t matter whether you let your car warm up or not, no matter how cold it is. Who’s right?
You’re both right — and wrong. Confusing, I know! But that’s only because neither of you are particularly specific about the specifics regarding this vehicular hypothetical, and that’s what will make or break the argument.

For starters, let’s talk about why this myth persists about warming up the car in the first place. All things being equal, driving your dad’s ice-cold Buick in ice-cold weather will result in one major negative side-effect: dogshit fuel economy. Score one for your old man, because according to the EPA, “a conventional gasoline car’s gas mileage is about 12 percent lower at 20 degrees than it would be at 77 degrees.” And at today’s fuel prices, you need worse gas mileage about as much as you need an asshole on your elbow.

Miles-per-gallon aside, there’s also the question of oil. As in, do you even know what kind of oil you’ve got pumping through your car’s veins? Without getting into the nitty-gritty of oil viscosity (more on that in a future column), some types of oil work better at certain temperatures than others. If you’ve been using oil better suited for warmer temps, then yeah, you’d best let your ride idle for 5 or 10 minutes and let that sludge turn runny, lest you blow out an O-ring or whatever.

But the fact is, it’s 2020, and the biggest reason for warming up a car in your driveway is mitigated by one, unassailable truth: That most, if not all of us, drive cars and trucks with electronic fuel-injection. 

You see, back in your dad’s day (most likely), most vehicles had carburetors to manage the air-fuel mix that’s used for energy to turn the wheels. And because gasoline doesn’t evaporate at the same rate in cold temperatures as it does in warm ones, sometimes those dumb ol’ carbs would screw up how much air would be needed to compensate in that air-fuel mix and the car would stall — all because of cold weather. 

Of course, the solution (and the basis for the warm-up-your-car myth) was to let the car run for a few minutes to allow that gas to come up to temp in order to avoid stalling. But modern cars don’t have carburetors; they use sophisticated computers and sensors to electronically change the fuel mix depending on how cold (or hot) it is, eliminating the need to warm up your car in advance of driving it.

“But what about fuel efficiency and oil viscosity?!?!,” your dad’s probably saying right now. Well, let’s not ignore the fact that if you’re worried about wasting gas, the last thing you should do is let your car idle away in the driveway for 10 minutes, which both increases fuel consumption (by a rate of 12 to 19 percent) and is bad for the environment on account of all the needless smog.

In the end, then, the only legitimate reason to preemptively fire up your engine in the winter months is for your oil. But really, that only holds if you’re using the wrong kind. Plus, it ignores one simple fact: That the best (and fastest) way to warm up a car IS to drive it. 

Game, set, match, pops.