I have compiled a list of ten automobiles which have had the most impact on the auto industry (and, in many cases, society). These aren't necessarily my favorite cars (they're probably not all your favorites either) and many weren't automotive best sellers.
That's OK, because this isn't a popularity contest; rather, it is a recognition of those cars which had the most profound impact.
And the winners are (in no particular order):

1. Model T Ford: Before the T, cars were mere playthings for the rich. Henry's T didn't just put America on wheels, it put the world on wheels.

2. Ford V8: While the 1932 Ford wasn't the first V8 produced, it was still such a new idea that people worried that gravitational forces might cause the bottoms of the slanted cylinder walls to wear out. They were wrong and every male in America lusted after the distinctive rumble which only a V8 can produce. That's why V8s are still made today. And how could hot rods have been developed without a flathead Ford V8 to move them? (What would they have used? Chevy sixes? Not too #@!%* likely!)

3. 1947 Studebaker: Its breakthrough styling instantly made every other new car look old-fashioned and forced every other car maker play to catch-up. The same envelope-bodied, three-box shape can still be seen in the designs of today's cars.

4. Jaguar XK120: This all-new postwar car popularized the sports car movement in America. Its sleek body, tuned chassis and powerful engine made everyone want one. Or want to copy one. The XK120 was GM's 'bogey' for the 1953 Corvette, although the Chevy missed the target by a country mile. If there hadn't been a Jag XK120, there probably would have never been a Corvette of any kind. Or a two-seat Thunderbird, either.

5. 1961 Lincoln Continental: It stopped the chrome-laden, tri-color, finned era dead in its tracks and reintroduced elegance to the American car market. I've met people who know nothing about cars yet fondly recall their parent's, neighbor's or uncle's Lincoln four-door convertible. Lincoln's clean looks were envied and copied by other U.S. car manufacturers. This car defined the Kennedy-era; it represented a New Frontier in auto design.

6. 1963 Corvette Sting Ray: The first American-made production sports car which could stand shoulder-to-shoulder with Europe's best. Independent rear suspension made it handle; the bulletproof 327 Chevy V8 made it roar; a four-speed Muncie tranny made it go and the striking styling was GM at its best and made the Corvette zoom out of the showroom. It was the embodiment of the same 'can-do' American spirit that put men on the moon. (And ... the 'Vette was the preferred ride of astronauts, by the way.)

7. Volkswagen Beetle: Small, technically obsolete and homely, it's a flawed but timeless car which was still in production at the dawn of the 21st Century. It taught American consumers that low-priced, reliable cars could be produced with a high quality of fit and finish. It made people rethink their car values - perhaps other values, too. It may have spawned a cultural revolution: did people become hippies, forsaking material values, because they bought a Beetle or did hippies just decide to buy Beetles, forsaking other kinds of cars? Hmmmm.

8. Datsun 240Z: The first affordable and reliable sports car. At $3,500 in 1970, it cost 35% less than a Corvette. It looked great, handled well and offered unmatched quality. Less temperamental than Triumphs, Porsche 914s or MGs, it killed-off these mid-priced Eurosportsters, yet helped to keep the sports car movement alive in the U.S. during the downtrodden Seventies.

9. Honda Civic: In the midst of the 1973 gas crisis, it offered a low price, decent build quality and a tiny, fuel-efficient engine that not only performed well, but could burn fuel cleanly. The little Civic's CVCC engine met the tough 1975 federal emission standards without a catalytic converter. It forced American car manufacturers to stop whining about government regulations and build better cars. If Honda hadn't built the Civic, Ford and GM would probably still be trying to sell us crappy Pintos and Vegas.

10. Lexus: Introduced in 1989 at a price 40% less than Mercedes and only 10 to 20% above Lincoln and Cadillac, this car (with no history and no heritage) rocketed past its pedigreed competitors to become the top-selling luxury brand in the U.S. And, amazingly, it was all done without rebates or rental car sales. Lexus has forced its competition to make better cars. One hundred years from now, they'll still be using the Lexus Marketing Jihad as a business case study at the Wharton School and at Harvard.
I limited my list to ten but, if I expanded it, the eleventh spot would have surely gone to Jeep - for obvious reasons. It helped win a war, for one thing. The twelfth spot would have gone to the original Mini. It popularized front-wheel drive and set the standard for small car packaging. Every FWD American subcompact of the 1980s owes a great debt to Alec Issigonis.