What temperature do car thermometres count?

well on my 206 the thermometer is located on the wing mirror so I guess its depends on local effects eg parked car on a tarmac drive is of course going to give a hotter than true reading although once your driving along it should normalise.

its not an exact precision piece of equipment either…

defiantly not the inside temp unless your car has climate control then yes that would show both indoor and outdoor temps but this should be noticeable as to which one is which?!

as far as outdoor temps go though I would imagine nearly all cars have the sensor in the region of the wing mirror away from engine heat etc so they should all give a reading of whats directly outside… !?

@Tobotron says it all!

They definitely measure the outside temp. Your girlfriends could well have been sat in the direct sunlight maybe even warmed by the surface of the car and this would have decreased with the cooling effects of the breeze as she drove away.

It depends. Some measure the temperature in the cabin and some measure the temperature outside. What does your car manual say about yours?

as an added comment to @Mat74UK suggesting that the thermometer was warmed by the surface of the car… my previous car was black and when it was sunny, it would always register a much higher temperature than it was. I got into the car once and it registered a full 10 degrees higher than what I had just seen looking on the internet. We all know that black absorbs heat. Maybe the color has something to do with it?

Car models have different features. Most measure outsude temperature. The ones that measure cabin interior temperature are typically tied into the car’s heating/cooling system. On the Mercedes Benz, it has a thermometer for outside temp on the dash, while the interior temp is clustered around the blower controls.

Most commercially available thermometers aren’t all that accurate. If you get three thermometers together, you’ll get three different temparatures.

Throw in all kinds of environmental factors like direct sun, shade, wind, engine temperature (radiant heat), materials involved and it would actually be mildly amazing if your car’s thermometer displayed the exact same temperature reading as the one you saw on the street.

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In my Honda, the temperature in the instrument cluster, under the speedometer, shows the outside temperature. (It even says ”OUTSIDE”).

On the dashboard, in the climate control section, I have two additional temperature displays. They show the “target” temperatures that the HVAC is attempting to reach (one for driver and one for passenger).

I have no display at all that shows what the current temperature inside the vehicle is.

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For example, on a hot Texas afternoon, the outside temp might be 100°F. My vehicle’s instrument display might show that as anything from 97° to 105°. Just depends.

And then on the dash, for the A/C, the last setting when I had left the car was 78°F.

Now, the interior of the vehicle when I first get in might be around 125° – 130°F… but the only way I’d know for sure would be if I brought in my own personal thermometer.

Thank you for your answers. Yes, I also figured it would probably count the ouside temperature, I just wasn’t sure whether different models had the sensors in different places.

And obviously, they’re not that accurate, they are just meant to give you a general idea (I wasn’t surprised at the 3.5C difference at all). But I was wondering whether being on a mirror would cool it down as the car is speeding, and warm it up when it’s parked (especially in direct sunlight).

In Germany you often get electronic signs on the side of the highway telling you both the atmospheric and also the ground temperature (especially in case of snow).

@Jack79 well a car with a temperature system is not a mobile weather station its just a gadget really so manufacturers arn’t gonna spend time giving you all this extra information on a mobile platform?! How would a moving metal object even be able to give a ground temperature reading anyway!?

as far as being on the mirror its for practicalities as much as anything…and the probe itself isn’t directly exposed so its not going to suffer hugely from wind/chill factors, this isn’t however true of urban hot spots such as your hot driveway in the summer etc.

its only a curiosity gimmic really though, and so its in your face as to there being ice on the road, I’m sure its also being used for climate control systems to regulate the temp of the air into the car but generally I’ve not given the temperature outside much thought beyond this.