Testing a Broken Windshield Hypothesis

Dear Car Talk:

Let me start off by saying I'm a scientist. I graduated from Boston University with a science degree. It was there that I met my wife, who also is a scientist. When we come across a problem, we attack it scientifically. Our problem: In the short span of three months, my wife has managed to crack the windshield of our 2008 Toyota Sienna XLE minivan three times. Each time required a replacement windshield from the fine ladies and gentlemen at a well-advertised automotive-glass shop. I do not fault the windshield repair shop in any way; instead, I hypothesize that it is my wife's driving behavior that may be contributing to her unusually high windshield consumption rate.

My driving instructor taught me that there should be a three-second distance between your car and the car ahead of you. I cannot comment on what my wife's driving instructor taught her, as I was not present to witness it. Needless to say, she leaves considerably less than three seconds -- in other words, she's a tailgater. My question is: Is it proven that following too closely behind the car in front of you exposes your windshield to more damage (rocks, gravel, road debris, a muffler from a 1974 Chrysler), thus explaining the need for more replacement windshields? Thank you.

-- Alex

Well, look, Alex. You're a scientist. So I'm sure you will immediately embrace the enlightening experiment I'm going to propose for you.

My hypothesis is that your wife is driving with inferior-quality replacement windshields. So to test this hypothesis, you need to go out this afternoon and buy her a 2016 Lexus LS 460. After she's driven her new car for three months, write back and let us know if she's cracked any more windshields. If not, then my theory is correct. And we'll all be happy.

If she gets three more cracked windshields with her new Lexus, then your theory probably was correct. But at least she'll be driving a brand-new Lexus, which should, in some way, make up for your attacks on her driving style.

Actually, your theory may be correct. It's likely that tailgating would increase the amount of debris that gets kicked up from cars in front of her. And minivans have large windshields that are right out in front as the first line of defense, unprotected from a long hood, as they would be on a sedan or SUV.

On the other hand, it takes a pretty big piece of debris to crack a windshield. It's not very easy. So it does make me wonder about the quality of the after-market windshields you keep buying.

So if you're not willing to blow $80 grand on your wife's new Lexus, take the Sienna to your Toyota dealer and have them install a bona fide, original-equipment Toyota windshield. And then see what happens in three months.

But I like the Lexus experiment better, Alex. Do an experiment, and ask your wife what she thinks