Model 3

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

edited November -1 in Model 3
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.
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Comments

  • edited July 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! :)
  • edited July 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.
  • @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.
  • edited July 2018
    It would be interesting to feed that back to 3M and see if they comment.
  • edited July 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.
  • edited July 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.
  • edited July 2018
    Well the thing is... I do not actually have a sunshade. Maybe I will just cover the windshield with towels or something.
  • edited July 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.
  • edited July 2018
    No worries, thanks TexasBob!

    Although, if you live in Austin, I'm happy to lend you my sunshades..it may or may not fit a Tesla, but they are flexible enough to also cover the A-pillar (?) if they are too big.
  • edited November -1
    I know that it blocks the heat from the sun shining through the tinted windows while driving.
  • edited July 2018
    Here is a video of the experiment (not very interesting, like watching paint dry)
  • edited July 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.
  • edited July 2018
    @breezin
    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).
  • edited November -1
    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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
  • edited July 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.
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