Experiment: 3M Crystalline Tint Makes ZERO Difference in Cabin Temp

Experiment: 3M Crystalline Tint Makes ZERO Difference in Cabin Temp

I did an experiment today to see how much the 3M Crystalline (CR70) tinting helps to reduce cabin heating when parked in the sun. The answer is "basically nothing" or at best of 1 degrees lower temperature after 30 minutes (116 degrees vs 117 degrees). Here are the details:

The Blue Model 3 has 3M CR70 on the sides and back window (the front cannot be done without risking blowing up the computer as discussed in other threads). The Black Model 3 has no tint. So question: is it worth it to get the 3M tint?

I cooled the cabins on both to 74 degrees. I then pulled them out into the courtyard in front of our garage where they could be exposed to the sun side-by-side with no shade. Then I watched and waited (I recorded the app as it tracked the temperature changes, so I may get around to editing a video of the experiment but it is a huge file so ...) To be sure, I repeated the experiment twice.

The two vehicles increased in temperature more or less in lock step both times. By the end of 30 minutes the Black M3 (no tint) was at 117 degrees and the Blue one (with tint) was at 116 degrees. (One could argue that since the black car absorbs more heat than the blue one, the deck was stacked in favor of the 3M tint.)

So the question is why? We know the tint rejects 97% or infrared and 50% of total solar (or at least that is what the manufacturer says), so what gives? It is probably the windshield and maybe (though I doubt it) the pano roof. Since the windshield is un-tinted because of that computer issue, there is still plenty of greenhouse effect there and even if we are rejecting heat from the side and back, it is not enough to make a difference.

In any case, proof positive that the 3M crystalline tint is a total waste of money to put on the sides and on the back if your intention is to a) keep the vehicle cooler while parked or b) help the AC work less when driving.

vishious911 | July 1, 2018

Awesome! Thanks for this experiment and findings :)

Do you think if we did the same experiment with older cars, we'd find improved results with tinting? I'm curious if Tesla is using better glasses to keep out the heat?

Also, hate to ask you this, but are you interested enough in trying out an experiment with sun shades you put inside the car on the windshield?

I live in Texas and drive a newer VW Passat. The sun shades definitely help keep the car cooler, and I haven't gotten any tinting on it. But I was planning to on the Model 3, but not anymore! :)

TexasBob | July 1, 2018

Updated results: I let the experiment run for an extra hour (by which I mean I did not get around to pulling the cars back into the garage). Tinted vehicle: 127 degrees. Untinted vehicle: 128 degrees. Mythbusted. I am not happy about having wasted more than $500. Grrrrrr.

Lonestar10_1999 | July 1, 2018

@TexasBob. Sounds to me like you conducted a very fair and objective experiment. I think you saved the consuming public a lot of needless expense and trouble with your findings.

Magic 8 Ball | July 1, 2018

It would be interesting to feed that back to 3M and see if they comment.

carlk | July 1, 2018

Not sure if the experiment is 100% accurate but your speculations of why there's no difference are probably correct. Pano roof is already well insulated. The windshield also receives more heat than side windows because of its size and angle. I do have my windshield tinted with PhotoSync 75 which is so light you can not tell its there even at night.

ptchang23 | July 1, 2018

@TexasBob. Another Texan here wondering if you could repeat the experiment with the sunshade covering the windshield, just like @vishious911 requested. Perhaps the heat coming through the front windshield overwhelms any benefit the tint would have provided?
I would really appreciate this information before I proceed with the tint on my model 3 I had planned ever since I reserved it on day #2.

TexasBob | July 1, 2018

Well the thing is... I do not actually have a sunshade. Maybe I will just cover the windshield with towels or something.

M3NOICE | July 1, 2018

@TexasBob . Interesting results. Thanks.
In addition to what others were interested regarding same sunshade on windshield, you could try different angles of the sun/cars - for the sake of science! ;-) The idea would be to understand where is the heat coming from? Thru your tinted windows or pano or windshield.

vishious911 | July 1, 2018

No worries, thanks TexasBob!

Although, if you live in Austin, I'm happy to lend you my may or may not fit a Tesla, but they are flexible enough to also cover the A-pillar (?) if they are too big.

lilbean | July 1, 2018

I know that it blocks the heat from the sun shining through the tinted windows while driving.

TexasBob | July 1, 2018

Here is a video of the experiment (not very interesting, like watching paint dry)

breezin | July 1, 2018

Like lilbean I hardly notice the heat on me though the windows when tinted. I don't realize how much of a difference it makes till I drive my wife's car with no tint. That alone is enough for me.

Same line of thinking... it might not make much of a difference when it comes to parked temps. Now it make take the tinted car longer to reach the high but in the end it heats up the same as with no tint. Now does the tinted car cool off faster? Does the tinted car use less power when cabin overheat protection is on? Does the tinted car require less cooling to maintain the same interior temps while driving? Plenty of other things to consider with tinted windows than simply parked temps.

vishious911 | July 1, 2018

Do your and your wife both drive the Model 3? The point that Bob was making was only for Model 3.

How would the tint make the car "lose" heat faster? I don't think there's anything inherent to tinting that would "absorb" the internal heat and "transmit" it out to the environment. In other words, this is what an air conditioner does, and not sure tinting ever can.

Parked temperatures are probably not as applicable to driving temperatures only if we're talking about the angle of the sun light. As his video was saying, unless your state makes it legal to tint windshield, I feel like parked temps is a pretty good indicator of the need for tints (or lack there of).

breezin | July 1, 2018

No wife drives a Mazda. But the amount of heat that is blocked from coming into the car has to mean something. I wasn't implying that tint would somehow transfer heat out. What I'm saying is that it blocks a lot of additional heat from coming into the car which would make it faster/easier to cool it off. It should also make it easier to keep the car cool... again because the tint is keeping heat out of the car. We see many 100+ days in my area and the sun coming through an untinted window is uncomfortably hot yet in the tinted CR70 car you hardly notice the heat at all. | July 1, 2018

I believe Tesla uses IR rejecting glass throughout. We know for sure this is done on the windshield and roof glass. This explains why tining has almost no effect, as the heat radiation is blocked before it gets to the tinting material. This makes sense as Tesla designs the car to be as efficient as possible. This means trying to reduce the amount of air-conditioning required, which extends the range in hot weather. I expect others use non-IR blocking glass that requires more A/C to compensate for the poor glass thermal properties.

Atoms | July 1, 2018

Nice experiment. If the sun did not shine from the sides, then the tint on the side windows would not have much of an impact. I know tint has always worked well on my cars so I will be tinting. I may add a near clear film to the front since that can be legal. May have to ask the doc for the prescription which allows up to 70% total on the front.

TexasBob | July 1, 2018

@breezin - my experiment tested the rate at which the cabin heated up not the total temperature it got to over a specified period of time. The tinted and un-tinted vehicle heated at the same rate. That means that the amount of heat entering the cabin was not appreciably different on tinted vs non-tinted. I suspect it is the windshield but TeslaTap could be correct that the windows already have IR rejection and the tint is redundant. I will probably just have to tape off the windshield and test again just to see. But to be clear (little pun there) based on these results and the fact that the windshield cannot be tinted in the M3, I will not be tinting our second car.

eplaskett | July 1, 2018

This seems like a very clever and well-controlled experiment. Thanks for doing it! I was leaning against doing any kind of tint, and this seals the deal. | July 1, 2018

@Atoms - Likely you're not in California, but any film on the front windshield (other than the top 4") is not legal in California. I doubt any film on the front windshield would make any difference to heat. Tesla already uses a very IR reflective layer within the glass.

dmaini | July 1, 2018

@texasbob am I correct to assume the roof glass has no film on both cars?? It would be good to check with the film on one of the roofs and with the $75 roof shade installed. Just a thought.

jjgunn | July 1, 2018

Didn't read the entire thread but how about repeating experiment with a sun shade in each windshield? I think that's where the heat is entering. It should definitely be different. Not by 1 degree either.

Really appreciate all the time you took to figure this out & post for us. Impressive experiment.

Tesla2018 | July 1, 2018

Where did you put the thermometer in the cars? Or does the car have a sensor somewhere that tells you the temperature?

I was doing a test on one of my cars and noticed that if I had the thermometer on the passenger seat the temperature was a lot warmer than if I had it in the footwell or hanging down attached to a string taped to the headliner in the middle of the car.

Daryl | July 1, 2018

I see in the video that the sun was almost directly overhead during the test. So there was very little sun incident on the side windows, and lots on the windshield, pano and rear window, which weren't tinted (or were factory tinted the same).

This test might be more informative if done while the sun is shining directly on the side windows.

When I first got my Model 3 I noticed that when driving directly into the rising Arizona sun, it felt hot through the windshield. After tinting the windshield (70% 3M Crystalline) it is much less intense.

TexasBob | July 1, 2018

@dmani The roof is tinted halfway up the back only (ie where the factory dark tinting fades out). The CR70 is very light so it looks very good and you cannot see the line at all. But the roof nor windshield is not tinted.
@Daryl - Yes it was high noon. I suspect it really is an issue with the windshield, but since we cannot tint that anymore (glad you did not have any problems with the ECU!) ...

Still I will try to update with a cover over the windshield next time I have both cars at home and free (wife was out of town today so it worked out).

I am excited about the aero wheel cover experiment I am going to try to talk her into helping with on Wednesday morning.

breezin | July 1, 2018

@TexasBob - Interesting.

"TeslaTap could be correct that the windows already have IR rejection and the tint is redundant."

I wish I would have paid closer attention. I had not planned to tint my M3 but as things got hotter around here I really noticed the heat coming though the side windows (I was not used to that having tint on my old car). I put CR70 on and swear I tell the difference. But clearly purely subjective.

TexasBob | July 1, 2018

@breezin I still think there might be a difference in heat coming through the sides but it is getting overwhelmed by the heat through the windshield. I will just have to cover the windshields of both and repeat the experiment :-)

wiboater4 | July 2, 2018

Glad you did that test. Takes a lot of guesswork out of things.

hokiegir1 | July 2, 2018

Interesting. We've got the Suntek 35 on side and back windows and did find that prior to tinting, the car was reaching 135 in direct sun (we had the car about 3 weeks before tinting), but after tinting, it was generally only getting to about 115-120. We added the roof shade recently, which also makes more of a difference than expected in our comfort, though not as much in the temperatures we've seen. We are talking about finding a windshield shade, because there is a LOT of heat that comes in through there, but we haven't looked for one yet.

maintreqd | July 2, 2018

As several folks have alluded to here, I think your issue is the untinted front windshield. A fair experiment would be to remove that variable entirely so only fully tinted versus fully untinted window glass is tested.

My wrap shop and I were discussing possibly doing tint but he said they don't do windshields. I think I've heard there is some risk to damaging the center console computer/screen when tinting the windshield; perhaps this is why?

Have other folks successfully (or unsuccessfully) tinted their front windshield? What was your experience if you have, with respect to heat blocking before vs after?

Daryl | July 2, 2018

@TexasBob "glad you did not have any problems with the ECU!"

I was concerned about that, but the tinting company assured me they had done Teslas before and were aware of the "water in the computer" problem. They took extra care to protect the electronics.

Turns out they did know what they were doing.

fernfern33 | July 2, 2018

I agree 100% with this test! And the windshield I don't think makes that much of a difference.

I too got 3M Crystaline installed on my 3. I did all side windows AND the windshield (70%). Yesterday the inside temp reached 142!!! Wasted $550!

Brian B | July 2, 2018

@arciniega.jerardo Forget the temp, i want to know how well summon works on your Model 3!

slasher0016 | July 2, 2018

When I got Crystalline on my Audi, it was explained to me by 3M that crystalline isn't useful (other than darkening and direct sunlight on limbs) if you don't do all the window surfaces. I think you should definitely redo the experiment without the windshield. All of that heat is coming from the windshield. Crystalline absolutely works...but you have to do the windshield. I never realized how big a difference it was until I traded in that Audi and didn't have crystalline anymore. I did 70 in the front, and 40s on the side and back. Now my Model 3 is noticeably was never ungodly uncomfortable inside my Audi even sitting in 100+ temps for 10+ hours.

hpn | July 2, 2018

i went with formula one tint....all around and the front windshield..noticed the car's interior is much cooler but still hot. works great when i drive..which to me is most important...any car left under the sun baking...will get hot...bc he will continue to penetrate into the car and it will absorb heat......

a covered car continues to heat .02 cents

lilbean | July 2, 2018

@arciniega.jerardo What was the outside temp? The highest reading I got was 121 degrees.

foodking | July 3, 2018

I'm interested to see how much a difference it makes with the windshield tinted. I tinted my current car with the cheapest film i could find online and got crystalline cr90 on my windshield recently. I'm driving around the current heatwave on the east coast and turning off the air conditioning because it gets kinda cold.

RIP ICE | July 3, 2018

@arciniega.jerardo - 142 is crazy hot. I sous vide my steaks at a lower temp than that!

I'm in LA, too, but my 3 was only 105 degrees when I left work at 1:30. No tint, full sun on asphalt parking lot. Mine is the white paint, though. Would that make a difference?

hokiegir1 | July 3, 2018


matt80206 | July 3, 2018

Man now I am on the fence... I usually go 50% tint too keep sunlight out... wonder if its the same...

httran26 | July 3, 2018

I don't have crystalline in my Model 3 but I do have it in my BMW i3. I'm very positive that these tint makes a difference. I feel the difference on my skin when I drive. I live in Texas.

For the Model 3, I have SunTek ceramic and did the full tint including the windshield at 70%. Before tint i got over 130 in the sun. After tint, it got to 103 in the sun. Both times about 1.5 hours in the sun.

On the i3 that has the cystalline, I had the car out in the sun one day with the windows partly down. After a while, I noticed the sun was hitting the leather part of the seat with half of it in full sun and other half blocked by the tint. I touched both parts. The one in the sun was burning hot while the part blocked by the tint was warm.

lilbean | July 3, 2018

You have to make sure that you got the genuine 3M film. The logo was imprinted on the tint and my installer showed it to me before the logo was removed.

httran26 | July 3, 2018

TexasBob, maybe we can experiment sometime. I live near Grapvine Mills in Grapevine, TX.

sroh | July 3, 2018

Tint absolutely helps with heat from the sun. We had one car that had 45% tint on the driver window. We had one SUV that was tinted in the rear but the driver's window was not. The amount of heat you feel when driving with the sun beating down on the window is noticeable.

With the sun overhead, tinted side windows will have a limited impact on interior temperature. But actual comfort from sun shining directly on you when driving is noticeable.

rxlawdude | July 3, 2018

@atom and @TTap,

In California, you can get a Dr.'s note and you can tint all windows and the windshield, but you then CANNOT drive the vehicle at night!

vishious911 | July 3, 2018

I don't think we're concluding tint is useless. We're just wondering if tint is any helpful on the Model 3 to be specific. I totally get historical proof of tint helping, and it sure did to my cars in the past as well!

I remember on the Model S range estimator page, one could check the impact of A/C on range. Seems like Tesla might take it a step forward to make sure there's some built-in heat protection (tint) from the windows to get the most range. Heck, they were even filling up the tires to like 40+ PSI to extract the last bit of miles.

TL;DR: We totally get tinting works on other cars. Just curious if it does make any difference on Model 3. Thanks!

Revelate | July 3, 2018

Interesting, speaking as a California homeowner with 3 floor to ceiling west-facing windows in direct sunlight from roughly 1 pm till 7 pm, the tinting absolutely made a difference (by about 4 degrees by the end of a day) which is huge when talking air conditioning bills. Incidentally I also have fantastic clarity at night so I'm wondering if legislation hasn't caught up with modern tinting or at least the various options of tinting.

Magic 8 Ball | July 3, 2018

Tinting for home windows can have some reflectivity where that is not allowed for car tints.

martinbogo | July 3, 2018

When you use a window tint -- it's important to check how much IR it blocks, not how much visible light it blocks.

XPEL Prime XR, for example, is quite good at blocking IR -- you can put a heat lamp on one side, and not feel the heat on the other.

martinbogo | July 3, 2018

I had 0% tint installed on my front windshield, and 50% tint on the side windows and rear

lilbean | July 3, 2018

You can drive at nIght with the windows rolled down. :)