One of the most common/universal symptoms of MS is heat sensitivity. Parked cars in direct sunlight are the worst. I've searched for solutions on reducing heat build up in my vehicle many times before, but the solutions have always been tedious or poor. I've never wanted to project my disability on everyone else basically saying, "Hey, look over here! I'm different!" Many of the heat reducing solutions would single your car out and they would take extra work to implement. So while Joe Schmo parks his car and leaves I'm still fiddling with a cover or something.
Last summer I used a powerful solar fan (not the weak one often thought of). It was around $100, but it still took a little extra time to set up each day & it still kind of singled my car out with a solar panel sticking out of the window. Also, I didn't notice any difference in heat reduction. I'm sure it helped some, but not much.
Last summer was horrible & I was dreading this summer for basically a full year. Determined to make this summer more bearable I took a few steps. I got more breathable shoes, insulated my car floor, replaced my failing thermostat (so my A/C wouldn't randomly cut out) & tinted my windshield. Out of everything I did, tinting the windshield has been one of the best things I've done.
The brand 3M is a well-known brand and makes a tint with heat reduction as its main goal. So, even though all my other windows look tinted, the windshield does not. I did it so I know it's there, but I can't even see it.
The sun hitting my chest through the windshield used to be too much, but now I don't even feel it. I look down and see the light on my chest & just grin.
While in the tint shop I was checking out all the displays they had. They had a heat lamp that you could put tints in front of to see how much the heat was reduced. The tint I was getting installed reduced the heat the best. I was so happy with my decision. It's the 3M Crystalline tint line...check them out.