How do heated seats in cars work?

how-do-heated-seats-in-cars-work?

Susannah Guthrie

heated seats cars

Heated seats often don’t seem like a necessity when you’re buying a new car, but flash forward to a particularly frosty morning commute and you’ll feel as though you can’t live without them.

With much of Australia battling through a so-called ‘polar blast’, this particular piece of automotive technology has proven a godsend.



But a quick jaunt through Google search terms proves our knowledge of just how heated seats in cars actually work is somewhat limited.

Beyond ‘person hits button, seat gets hot’, not much is known about the magic of the bum-warmers that have graced cars since 1966.

So, we asked some of the experts to answer our burning (pardon the pun) questions.



Can heated seats burn you?

It’s possible, but not common. There have been reports of incidents overseas where drivers have been burned by their car’s factory-fitted heated seats, but these cases typically involved drivers with paraplegia or other forms of decreased sensation.

Most recently, US media reported that a faulty heated seat in a 2013 BMW X5 overheated and burned a hole in the seat and caused an injury to a six-year-old boy.

However, according to a spokesperson for the Australian Competition and Consumer Commission, there have been no locally reported safety issues with heated car seats in the last 12 months.



Experienced mechanic Matthew Guastella of Automotive Advocates told Drive he was yet to encounter an issue was a factory-fitted heated seat.

“Of all the things I’ve fixed in cars, heated seats have not been one of them,” Guastella said.

Are heated seats bad for your health?

Some of the most-Googled questions around heated seats relate to some fairly confronting health issues: Can heated seats cause infertility? Yeast infections? Hemorrhoids?!



Thankfully, that’s mostly the stuff of urban legend – although there is potentially a very small connection between heated seats and male sperm production.

“Temperature is the issue – if it is less than 30 degrees Celsius it is unlikely that the heat will affect spermatogenic activity to interfere with fertility, especially for short-term exposure,” Dr Peter Temple-Smith, Senior Research Fellow at the Department of Obstetrics & Gynaecology at Monash University, told Drive.

“There is a recent paper on the effects of saunas on sperm production showing a transient effect. The regular use of saunas caused a reduction in spermatogenic activity and sperm viability … but as soon as the use was reduced significantly or stopped normal spermatogenesis resumed after about 60 days.”



As for heated seats and female fertility, Dr Temple-Smith said there is “unlikely to be an effect”.

“The female reproductive system [is] always exposed to, and functions at, normal body temperature so a heated seat in a car would need to be producing a temperature that was unlikely to raise body temperature (my hypothesis).”

Another known health issue on record is “toasted skin syndrome“, with dermatologists in the US telling Reuters of a rash that can arise after prolonged exposure to heated seats.

It’s not serious and the treatment is simply avoiding heated seats.

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When were heated car seats invented?

While Volvo can lay claim to the three-point seatbelt, we have General Motors to thank for heated seats – or one GM employee in particular.

In 1951, Robert L. Ballard – an engineer for General Motors – filed a patent for the ‘Automobile Seat Heater’.



Despite its early invention, it took 15 years for the technology to appear on the first production car, the 1966 Cadillac Fleetwood, which featured heated front seats as a $US78.95 optional extra (over $AU1000 today, adjusted for inflation).

The first time they appeared as a standard inclusion was on the 1972 Saab 99, 96 and 95 models, where they were activated when the cars’ ignitions were turned on and the cabin temperature was below 57 degrees Fahrenheit, or roughly 14 degrees Celsius.

In turn, a thermostat would detect when the seat’s temperature reached 82 degrees Fahrenheit (27.7 degrees Celsius) and the function would turn itself off.

The manual for the Saab 99 even described a cold seat as “a medical risk as well as uncomfortable”.

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Above: an excerpt from the manual for the 1972 Saab 99 sedan – the first car to offer heated seats as a standard feature.

How hot are heated seats?



Our findings suggested heated seats operate at a range between 30 and 45 degrees Celsius.

However, getting a manufacturer to disclose specific temperatures proved a little more challenging.

“We do not disclose temperature-related information. Temperatures vary depending on conditions,” a spokesperson for the Mazda Corporation’s Research and Development department told Drive.

The only information they provided was in relation to the individual settings for seat heaters in Mazda cars, which function as follows:

  • High: Rapidly heat up in low-temperature environment and provide enough warmth for the occupant
  • Mid: Provide moderate warmth
  • Low: Provide comfort with balanced temperature

Mazda’s spokesperson added that no two car brands are the same, explaining: “We think each OEM has its own, unique way of thinking behind the temperature settings they develop for their seats”.

Meanwhile, Vivienne Brando, a spokesperson for Vehicle Technology at Mercedes-Benz Cars, was similarly vague on specific temperatures but explained the following:



“The driver seat as well as the front and rear passenger seats are equipped with a three-step seat heating which can be activated manually via the door control panel. Depending on the surrounding temperature, the seat heating reaches an individual temperature. Aiming for a comfortable and pleasant warmth.”

In summary, it appears the seat heating system takes into account both the individual setting chosen by the driver, as well as the surrounding temperature, to calculate the ideal warmth required.

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Do heated seats have to be leather?

No – according to the experts, seat heating works well with either fabric or leather seats.

“Mazda’s seat heaters are controlled to reach target temperatures no matter what seat material is used,” Mazda’s spokesperson told Drive.

Meanwhile, while Mercedes-Benz engineers don’t have to contend with fabric seats, their standard systems work with all trim levels.

“The standard seat heating is suited individually to each material group,” said Brando.



“The Warmth Comfort Package [which works to also heat other interior elements like the armrests of the centre console and front doors as well as the door centre panels] is well suited for leather seats. It includes seat heating that reacts particularly quickly – depending on the surrounding temperature and the seat’s temperature.”

Can heated seats get wet?

In short: not really.

“I’ve only heard of people spilling their bottle of water on a factory-fitted heated car seat and, in that instance, it didn’t create issues, and I told the customer to just blot it with a towel,” Guastella told Drive.

“It didn’t create any issues but that’s not to say it won’t. Leather options might repel water a little better, but material might absorb it.”

Guastella’s official advice was to be safe rather than sorry. If you do happen to get your heated seats wet, avoid using them until you can get to a mechanic or dealership and have them checked for any safety issues.

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Can you buy aftermarket heated seats?

You can purchase aftermarket heated seats for cars, but that doesn’t necessarily mean you should. Or, at the very least, you should proceed with caution.



“There are aftermarket seat heaters that slip on like a seat cover and plug into your 12-volt socket,” Guastella said.

With those, Guastella advised checking they “don’t interfere with the factory restraint system” and are “airbag compatible”.

“I’ve also heard of upholstery shops fitting them underneath the upholstery – I don’t know the ins and outs of that, but my concern is how will it react with the seat material, plus lots of seats have airbags in them and then it becomes an ADR (Australian Design Rules) issue,” he added.

“Another issue is that you might create added electrical load on your car’s system with aftermarket seats, so you might blow a fuse.”

Meanwhile, manufacturers typically advise against fitting aftermarket heated seats to their cars.

According to Mazda’s spokesperson: “Mazda takes pride in designing its seats to offer drivers an optimal driving position, fitting aftermarket heated seats risks jeopardising this driving position. Thus, we cannot and do not recommend fitting aftermarket seats. Mazda’s heated seats are not developed in consideration of fitting aftermarket heated seats”.



Susannah Guthrie

Susannah Guthrie has been a journalist since she was 18, and has spent the last two years writing about cars for Drive, CarAdvice, CarSales and as a motoring columnist for several in-flight and hotel magazines. Susannah’s background is news journalism, followed by several years spent in celebrity journalism, entertainment journalism and fashion magazines and a brief stint hosting a travel TV show for Channel Ten. She joined Drive in 2020 after spending a year and a half at the helm of Harper’s BAZAAR and ELLE’s online platforms. Susannah holds a Bachelor in Media and Communications from the University of Melbourne and cut her teeth as an intern for Time Inc in New York City. She has also completed a television presenting course with the National Institute of Dramatic Art. She lives in Melbourne with her husband and her one-year-old son who, despite her best efforts, does not yet enjoy a good road trip.

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