Winter warm ups trade fuel for comfort

With a remote starter, a wait of 10 to 20 minutes, and some additional gasoline, a vehicle like this Volvo V90 Cross Country can greet its driver with a warm, cozy cabin after it’s been parked outside in winter.

Every morning I’m out for a walk when the earliest early birds are preparing to leave home for their commutes to work. This time of year, when our bleak winter mornings chill you through the puffiest down jacket, I notice cars warming in driveways.

Started from inside the house with a push-button remote starter, the unattended vehicles run at their low, idle engine speed . . . and run and run, idle and idle, until their engines warm up completely.

Of course, even at idle, when the engine spins at its slowest, lowest rate, it’s still consuming some gas.

And some drivers wait for more than just their engines to heat. Many also wait until their car’s cabin has warmed up too. That’s a lot of empty space to make toasty.

It explains why I’m often surprised by how long some cars are left to idle in driveways unattended. I’ll sometimes walk past a vehicle warming outside a house, walk out a ways before circling around and coming back, and pass the same car still stationary and unattended, while its tailpipe shoots jets of smoke that tumble and rise into the cold morning air.

That’s what it takes to raise a car’s cabin to a comfortable temperature, especially after a full night outside when the air has plunged to 20 degrees, 10 degrees or lower.

“We tell people it takes between 10 and 20 minutes to actually warm up the engine and warm up the interior of the car,” said Andy Sussman, director of operations at Auto Sound, a vehicle-accessory specialist in Middleton – with other locations in New England.

At this time of year especially, installing remote starters is a big part of Auto Sound’s business. The company also specializes in configuring high-end audio systems for vehicles, and it installs such accessories as power sunroofs, navigation systems, leather upholstery and obstacle-detection cameras.

Vehicle cabins are heated with excess heat from the engine. That cast-off heat is transferred from the engine’s circulating coolant – the fluid we call “antifreeze” – and blown into the cabin by a fan.

But the engine has to heat up itself before it has excess heat to give. So running the cabin heater too soon actually works against you: it only blows more cold air into the passenger compartment. Worse, as a cold engine’s temperature begins to rise, blowing the little heat it has gained into the cabin sucks warmth away from the engine. The engine then needs more time to fully warm up itself.

I’m a frugal sort who likes to coax as much mileage out of the gas in my car as possible. Letting an auto idle works against that.

On the other hand, who wants to start their day by settling onto a car seat that feels like a slab of ice?

It’s tough to find a single figure for how much gas cars use when warming up in a driveway for 10 or 20 minutes. You can do it for your own particular vehicle if it has a fuel-consumption indicator as part of a trip computer or vehicle information center – which many cars have today. Track your average fuel consumption through a week of early-morning vehicle warming. Then track your average through a week when you skip the warm up and head off to work in a cold car. A little math will lead you to the difference in fuel use between the two weeks.

But with so many sizes of vehicles, with engines that are large, small, high powered and low powered, and with cabins of so many dimensions, any universal estimate is little more than a guess. I did some research, crunched some numbers, and went away frustrated. My best estimate is that you’ll burn one additional tank of gas by warming your car through about four and a half months of cold-season driving.

At current gas prices, and figuring that your tank holds, oh, let’s say 14 gallons of gas, that about 34 bucks.

Andy Sussman, the operations director at Middleton’s Auto Sound, pointed out that the efficiency and precise operation of contemporary engines minimizes gas use during warm up. Many more vehicles today use smaller, four-cylinder engines that are turbocharged to provide extra power when needed, but which sip fuel when they idle.

“It’s not like the old days,” he said. “In newer vehicles, the gas usage is a fraction of what it used to be.”

Sussman noted that remote starters also are popular in warm climates. But whereas we hardy northerners use them to pre-heat our autos in winter, drivers in Arizona, Florida, Texas, and the like use them in summer to pre-cool their cabins. They’ll start their engines remotely and let it turn the air conditioner for a while, rather than climb straight into a car that has sat in 100-degree sunshine.

Car manufacturers have noticed the appeal of remote starters. The feature is included in a growing number of the straight-from-the-factory models that the companies send me to evaluate – especially in the higher-priced, upper trim levels.

In Middleton, Sussman reported that even with the devices installed in more new cars at the factory, Auto Sound’s installations of remote starters hasn’t diminished.

“Our volume has not decreased at all,” he said. “During the winter we install thousands per month.”

I’ll always be an economical driver. But I’m a Merrimack Valley driver too. As I’m writing this, I see that the temperature here is expected to drop to 14 degrees overnight.

Maybe it’s time to consider a compromise. An engine warms up faster if the cabin fan isn’t running and sucking away some heat. Perhaps I can live with remotely starting just the engine, leaving the cabin heater switched off. I could give it, oh, four or five minutes.

I’d still be climbing into a cold cabin to back out of the driveway. But with the engine fully heated, I could crank the fan to high and feel heat very quickly.

Jeffrey Zygmont is an author of fiction, non-fiction and poetry books, and a long-time auto writer. Contact him at


Recommended for you