As I posted a few weeks ago, I remember this show very well and have seen pretty much the entire series. The prizes and cars were added in the fourth week (I have no idea why remember this!)... and yes, originally they had high-end Cadillacs (Sedan deVille. Eldorado) and Chevy's (Corvette and Camaro)... I think they stayed until won... and the champion did retire then... then they changed the car weekly and got rid of the $5000 cash prize card in the main game after a few weeks... They offered Pontiacs (Fiero, Firebird, Sunbird, Sundbird convertible), the Jeep Wrangler several times, and the Renaults (GTA, ALliance).... (please don't flame me for suddenly getting Zachitis)...
And yes, the show did speed up... after a week or two he won;t explain the rules and the audience and educated guess questions add more variety (started the same time as the car and prizes)....
One thing I believe I remember was at the end of the summer reruns for the last 4 to 6 weeks or so they aired shows that never aired before they switched to the cars and prizes... don't know how many total shows were made with this basic format...
Enjoy!