15. Chevrolet Impala ZL-11
In 1963, Chevrolet introduced the limited but highly influential Z-11 option on the two-door Impala. The idea behind the Z-11 was to introduce the best street/strip technology in one model. The first order was to shed some weight by using aluminum panels, grilles, hoods, and fenders.
The radio and heater were gone, and they stripped the interior of all unnecessary luxuries. Chevrolet built only 50 to 57 Impala Z-11s in 1963, and less than 10 survive today. This was another example of keeping the package secret, so the public didn’t know this model existed.