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The answer: 1973 Dodge SE (South Africa)
That's one of the oldest old wive's tales in the book.
Seriously. If you could make a gas-powered internal-combustion car that got 250 MPG, they'd be making them! Whoever made it would sell hundreds and hundreds of thousands of them and make a huge profit! Do you think the automakers would be spending millions of dollars trying to wring out a few more MPG from their cars if they could build a 250 MPG car?
Why aren't there any? Simple. It's impossible.
Seems to me that the cells needn't be compound-curved. You could have a steel inner roof panel (to maintain rollover standards), then smaller flat photovoltaics arranged in series in an array to sort of conform to the curvature of the roof, then a compound-curve glass roof on top. I suppose cost would be the hangup.
Yeah... that was the original question! Why haven't they done so? The subject matter seems like a no-brainer. If ever there was a subject that you could practically guarantee would sell well, it's a '57 Chevy.
Don't know... but that model not only gave you a choice of coupe or convertible, they even threw in a custom roof, too! And that kit was tooled when dinosaurs still walked the earth.
They could do it then, but some of you say they can't do it now???
Could have something to do with rollover/crashworthy standards? Just a guess, I may be totally off-base. But that does sound smart... on a sunny day, if you're parked outside (say, at work), you could be charging up your car for absolutely no cost.