The changes in the 1993 Corvette includes, a four-bolt main bearings, a Mobil 1 synthetic oil requirement, platinum-tipped spark plugs, and an electrical, linear exhaust gas recirculation (EGR) system for improved emission control. A special 40th anniversary package, the RPO Z25 was made available on all Corvettes which features a Ruby Red metallic exterior, a Ruby Red leather sports seats a power driver seat, and a special wheel center trim and emblems. One of the great changes that 1993 Corvette has is the Passive Keyless Entry that is standard in all Corvettes, when the owner approached the car the doors would unlock.