25. C3 ZR1 and ZR2
Complex Says: The ZR1 was a competition spec 'vette, and each car came with the LT-1 engine. In order to make the cars race-ready, GM fitted them with an improved cooling system, a revised suspension, and some chassis upgrades. Power windows, power steering, air conditioning, rear window defoggers, and radios were not available. The ZR2 was only made as a 1970 model year (although it was released in 1971), and it featured the same upgrades and restrictions, with the exception that it had the 454ci (7.4L) LS-6 engine. The LS-6 was the only Corvette engine in '71 formulated to run on premium fuel.