On the other hand, imagine a car crash.

30 J/kg absorbed radiation won’t just kill you in <48 hours, it’ll give you seizures and diarrhoea first.

That would make people drive more safely.

I met someone who tried to kill themselves by driving into a wall.

The only way I’d be comfortable living in the same city as a nuclear powered car is when it’s an electric car and the grid it charges from is nuclear powered.

There were designs for this but AFAIU the amount of mass needed for shielding the reactor would make it impractical. Not sure if technology has changed much but presumably the only way to get around this is to reduce radiation as the mass of shielding has more to do with fundamental physics I think.

My understanding (as a lay person) is that metal foams have revolutionized the area of shielding. I would imagine that many designs that were once impractical, may no longer be so given the new light-weight shielding technology.

Interesting, I was not aware of this - the problems I described were from designs in the 1960s