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Do Heated Seats Use Gas? (Explained By A Mechanic)

Do Heated Seats Use Gas? (Explained By A Mechanic)
Fact Checked and Reviewed by: Kris Jackson, ASE-Certified Mechanic
Kris Jackson has been a mechanic since 2010 after graduating from UTI. He’s worked with several master mechanics and holds several ASE Certifications. You can read more about Kris here.

A penny saved is a penny earned and when it comes to your car one of the best ways to “earn” those pennies is by improving your gas mileage. There are plenty of ways to get more out of every gallon, from keeping your tires inflated to driving slower. But what are some of the comfort options- like seat warmers? 

Do seat heaters use gasoline and is it worth it to skip them to save cash? 

Heated seats are powered by electricity via the alternator. That means seat warmers don’t use fuel directly but the alternator does use fuel (via the engine) to generate electricity. However, the amount of fuel used is very small and the typical seat warmer uses around $0.01 worth of gas per hour per seat so it’s not worth getting chilly to save gas. 

I’d rather step into a nice and toasty car than save a penny an hour on fuel so this one seems pretty clear cut to me! The impact on your mpg is almost too small to even measure and it’s also even less savings and fuel usage than using your heater, which only costs around $0.04 an hour to run.  It’s also worth pointing out that most accessories in your car will use some fuel. I’m talking about everything from your car’s headlights to the stereo system so your heated seats aren’t special in that regard. 

That’s the quick answer and it will keep your backside warm on a budget.  But if you want to look at a few other scenarios or get a better understanding of how I came to this conclusion, stick around as we take a closer look. 

How Do Seat Warmers Work? 

Let’s start by taking a closer look at exactly how seat warmers work so we can understand when fuel usage comes into play. Here’s the step-by-step process without too much technical jargon:  

It All Starts When You Flip The Switch

Your seat warmers run on electricity and when you flip the switch, electricity from your vehicle’s battery and alternator power up the heating system for your car.

Beneath the seat’s fabric or leather, there’s a network of thin resistive wires. When electricity flows through these wires, they resist the current, and this resistance generates heat. This is the same basic principle as the heating element in a toaster or an electric stovetop.

Your Alternator Uses Fuel To Keep Your Backside Toasty

While the battery does provide some of the power for the seat warmers, the alternator takes all the burden once the engine is running. However, the alternator is already active and powering things like the headlights, radio, and air conditioning. That means the additional wattage (and therefore fuel) required for the seat heaters is extremely low. 

Exactly How Much Fuel Does A Heated Seat Use? 

When you activate a heated seat, it begins drawing electricity, increasing the load on the alternator. However, the energy demands for a heated seat are very low. 

It’s impossible to give an exact number for every car, but we can estimate that at the highest setting, a seat warmer will take around 25 to 50 watts of energy per hour for each seat. We can convert that to horsepower (considering 746 watts equals 1 horsepower), and we’re looking at a meager increase of approximately 0.03 to 0.07 horsepower.

Putting that in terms of fuel consumption, we see that an increase of 0.03 to 0.07 horsepower for a heated seat might result in an additional fuel burn of roughly 0.001 to 0.002 gallons of gasoline per hour for standard gasoline engines under typical conditions. This increase is equivalent to almost a penny depending on the current cost of fuel. 

Double those numbers so that you have both seats on the highest setting and you might end up with a savings of a penny or two every hour. I’d rather be warm and comfortable than save a couple of cents! This is also much lower fuel usage than other accessories in your car like the defroster (which you really can’t go without). 

But How Does This Play Out In The Real World? 

If you’ve already been researching this for a bit you might have stumbled across a video like this: 

In the video, the driver covers the same distance twice. First with the seat warmers off, then with them on. He finds a 1% increase in fuel usage with the seat warmers on.

But that’s more fuel usage than what we’ve laid out here- so what’s going on? 

Well, a 1% variation in fuel usage between two trips is well within the normal range we’d expect.  Changes in driving style, traffic, wind conditions, tire pressure, and more could all account for a 1% difference in fuel usage. You can see much bigger variations in your average MPG just by driving slower

What About When The Engine Is Off And Seat Warmers Are On?

While it’s a much more uncommon situation, there are times when you may have your car’s seat warmers on but the engine off. 

In this case, the seat warmers are pulling all their power from the battery since the alternator is only on when the engine is on. However, once the engine is turned on, the alternator will have to work a bit harder to recharge the battery. That extra work will require a little extra fuel as the engine provides the power needed by the alternator to recharge the battery. 

Still, this is all pretty insignificant when you look at the actual fuel consumption or the pennies per hour that it will cost to run.  

Closing Thoughts

Nobody wants to waste gas or money so it’s natural to wonder if our toasty tush is costing us a pretty penny. 

Turns out, it isn’t and other features of your car like the A/C use much more fuel

Turning off the heated seats isn’t going to save you more than a few pennies so drive safe and stay warm this winter!

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