No you don't. Thorium reactors are actually breeder reactors which run off of U-233, one of the byproducts of breeding U-233 is U-232, which emits gamma rays li

No you don't. Thorium reactors are actually breeder reactors which run off of U-233, one of the byproducts of breeding U-233 is U-232, which emits gamma rays like nobody's business. The only way to stop gamma rays is with lots of shielding made out of high-Z materials, like lead, which is inevitably super heavy. So you'll either get a multi-ton car that crawls or a light-weight car that gives you cancer or a lethal dose of radiation if you drive it more than a few hours.