Does "vent" function actually reduce vehicle's interior temperature?

[dave999z]

When my M3 is parked in the driveway and the interior reads (per the app), say, 104F, and I "vent" the windows, an hour later the temperature hasn't changed. Perhaps it only really works if it's windy out? Just curious about other's experiences. Cheers.

 

[Puddles]

I haven't done a "wit or witout" test but I am often impressed at how relatively cool it is inside the car on a hot sunny day, compared to other cars I've had. I credit some combination of the following:

Vented windows
Overheat circulation (set to fan only)
Super high-tech low-e window coating on the roof

A black car with a black interior sitting outside in the sun by all rights should cause my leg fat to sizzle like bacon when I get in, but despite all reason, instead, it's usually almost comfortable.

 

[insaneoctane]

I've noticed stagnation of air (temp) with the sensors. I will see the car shows 99 degrees, so I turn on the air and the interior temp jumps to like 115 once it's moving across the sensor. Wondering if your setting a bit of this with your vent observation

 

[strykeroz]

I find vent very handy in the summer here. Converting to your money I'd expect the interior to get over 140F in no time on a 95F day if the windows are up. Before vent feature arrived I used to burn a lot of electrons running the AC while the car was parked outside my office out of concern for the interior. An kind of breeze certainly helps, and a good windy day will mean no need to pre-cool the interior before driving.

Perhaps it's more effective the hotter it is out?

 

[Gizmo35]

Yes in theory it should work, hot air rises, cold air falls. High pressure seeks out low pressure. I use vent to let the hot air out the car while I turn the ac on about 10-15 mins before leaving work. I always arrive to a cool car.

 

[SageBrush]

When my M3 is parked in the driveway and the interior reads (per the app), say, 104F, and I "vent" the windows, an hour later the temperature hasn't changed. Perhaps it only really works if it's windy out? Just curious about other's experiences. Cheers.

IIRC vent runs for 15 minutes.

If your windows already allow airflow vent will have little effect.
Vent is a superb tool, but you do have to understand how to use it.
----

Today was bright sun and about 85F in my corner of New Mexico today. I always park facing the sun and use a sunshield. If I can I park in shade, and if I am home or feel secure away from home I leave my windows cracked open for ventilation. If I left my windows closed I run the vent setting for ~ 5 minutes before I enter the car. I ran my city errand at Noon today. 4 miles each way, about 30 minute stop in the middle. A/C auto set to 68F. Round trip was 113 Wh/km (182 Wh/mile), or about 5.5 miles per kWh.

The Model 3 is an outstanding hot weather car. Cold weather, not so much but the Model Y is improved.

 

[strykeroz]

IIRC vent runs for 15 minutes.

I leave my car parked with vent all day so it doens't time out for me. I have to remember to shut them for afternoon storms.

 

[Chisale]

I've found it helps, especially if it's cooler and at least slightly windy. If the ambient temp is 95 and calm then not so much. It does keep the fan from running as much.
However, I have also found that the interior temperature that it tells you in the app is often not remotely correct. Not sure if that's because the sun is hitting the sensor directly or some other reason. But generally, I agree with Puddles above that the car doesn't get as hot as many others I've had with lighter colored interiors.

 

[john5520]

From what I've seen, venting slows the temp's rate of climb. I've used it and it helps, but now I've been relying more on the cabin overheat protection to keep things in check. The only issue I've run into with it is the fact that it does not turn on automatically the next day if the car is parked and not used for a while. Thanks to another thread, I've now learned a trick to turn it on from the app: turn on Climate and then turn it off. I usually let it get to under 100F before turning it off. COP will then keep it around 100F for the rest of the day on fan only. If I forget to turn it on, temps can climb to over 140F on a hot day. I also have a sun shield to protect the dash and console which I highly recommend for those who park in the sun. Unfortunately, I did not have time to tint before the Covid crisis. And I'm not trusting enough to get it done at the moment.

 

[CyberGus]

There's a joke about a guy walking though the desert carrying a car door, so that he could roll down the window if it got hot.

If the air temp outside is 101, then everything outside is 101 (or moving towards it). However, an object in direct sunlight will be getting extra radiated energy, losing some of that to the "cooler" air, slowly rising.

But if you have something like a car that lets in the radiated energy (through the windows) without access to the outside air, the temperature inside will climb precipitously.

Therefore, venting a car will only bring the temperature down closer to the ambient temperature. And this only helps if it was trapping the additional heat of solar radiation. A car in the shade will have the same internal temperature as ambient, regardless of the windows being up or down.*


*Of course, with the windows up, it will take longer for the interior to reflect the changes in ambient temperature.

 

[Matsayz]

IIRC vent runs for 15 minutes.

If your windows already allow airflow vent will have little effect.
Vent is a superb tool, but you do have to understand how to use it.
----

Today was bright sun and about 85F in my corner of New Mexico today. I always park facing the sun and use a sunshield. If I can I park in shade, and if I am home or feel secure away from home I leave my windows cracked open for ventilation. If I left my windows closed I run the vent setting for ~ 5 minutes before I enter the car. I ran my city errand at Noon today. 4 miles each way, about 30 minute stop in the middle. A/C auto set to 68F. Round trip was 113 Wh/km (182 Wh/mile), or about 5.5 miles per kWh.

The Model 3 is an outstanding hot weather car. Cold weather, not so much but the Model Y is improved.

I too find the Model 3 to be a great car in HOT weather. I'm in Las Vegas where we've had 104-108*F the last few days and the car has been great. I left the A/C "on" while I ran into the store and lost 1% range over 20mins. Also, having the app you can always adjust the temp before getting to the car. I haven't really used VENT yet but maybe I'll try it this weekend.

 

[jrweiss98020]

When my M3 is parked in the driveway and the interior reads (per the app), say, 104F, and I "vent" the windows, an hour later the temperature hasn't changed. Perhaps it only really works if it's windy out? Just curious about other's experiences. Cheers.

Once the interior is heat-soaked at 104°, it will be difficult to reduce the temp just by opening the windows a bit. Use it as a preventive measure, so it [hopefully] doesn't get that hot. The more wind from one side, the better it will work.

Remember that by default, the AC will work to keep the interior temp below 105°F. That means that it could have been at 104° for a LONG time before you noticed it...

 

[SageBrush]

Once the interior is heat-soaked at 104°, it will be difficult to reduce the temp just by opening the windows a bit.

Vent (whether active or passive) will not reduce the interior temperature below ambient.
Put another way, vent reduces the greenhouse effect. Used smartly and in combination with shading in front of the sun pretty much keeps the car interior air (and your all important seat and wheel) at ambient.