Cars newer than 25 years must meet all federal safety and emissions standards for their year of manufacture or they endo into a bureaucratic brick wall. If you wish to import them privately - see www.nhtsa.dot.gov/cars/rules/import for a thorough run-down of the Federal Imported Vehicle Safety Compliance Act of 1988 and its subsequent amendments. It's enough to make your head spin.
Let's scrap the 25-year rule. The differences between U.S. vehicle regulations and the rest of the car-producing world are pretty minimal. Our government welcomes on the road an old safety-free smog belcher like an unloved Olds while treating the catalyzed, crashable, newer but un-federalized import like radioactive waste?
Let's change this.