Basically it is fairly simple to design a safe vehicle, or an
efficient vehicle, or a non-contaminating vehicle. The problem is that
the car buying public doesn't want one.

I think most people (except for complete idiots) would prefer a more
efficient vehicle but the car companies aren't force by the Gov't to
increase efficiency so they don't.
I was at a neighbors BBQ right about the time gas had reached $3/gal. We
were talking about fuel mileage (of course) and another neighbor quipped
that the hybrid vehicles were something, getting 35 mpg. My thought was that
the car companies had the hybrid technology sitting on the shelf waiting for
the oil people to give us the shaft, which made the new cars pretty
attractive.
This guy is about 10 years younger than my 49 and so doesn't remember the
Datsun B210 or the similar model Toyota getting mid to high 30s in the 70s
fuel crunch.
What other reason could there be for fuel efficiency not to have improved?
After that time in the 70s it actually went backwards. I know emmision
controls rob some power but we have computer controlled fuel injection now.
Was this created just so that we would have to take our cars to the shop
instead of working on them ourselves?
When people scream conspiracy, I think they're at least half right. The rest
is just crap goverment.