Car: Pontiac LeMans Sprint
What makes it special: The Sprint package was an option on all Pontiac Tempest and LeMans models, ( except station wagons) that included a hopped-up 4-barrel version of the 230 cu in OHC six that also included higher compression ratio and a hotter cam, resulting in 215 horse power, along with an "all-syncro" floor-mounted three-speed automatic transmission with a Hurst shifter, a suspension kit, and body striping.
What made it famous: For 1968, the Sprint OHC six had gone from its original size of 230 inches to 250 cubic inches, and the horsepower had increased from the original 207 hp to 230 hp in its final version. This engine when teamed up with a 4-speed manual transmission was capable of high 14 second quarter mile times in a Tempest at speeds in the low 90 mile an hour range, making it surprisingly faster than cars with small V8's of the day.
Why I would want one: To be honest, in most cases, I'd run screaming from any inline-6 cylinder car, but this is something different. I like the idea of a killer inline-6 that could wow the pants off some of the more common V8's of the day. You gotta respect that. Plus, it's in the engine bay of one of Pontiac's more attractive offerings to boot.
Fun fact: The Sprint-optioned Tempest and Le Mans models were not very popular during the mid-to-late 1960's due to their being outsold by the big V8 GTO that was heating up the muscle car wars. The Sprint option and SOHC 6-cylinder engine were discontinued after 1969 with an ordinary Chevrolet-built 250 cu in OHV 6-cylinder engine becoming the base engine from 1970 to 1976 in most Pontiac intermediates.
( 1968 Pontiac LeMans Sprint photo from collectorcarads.com )