I know, I know, they look the same. Well, they don't. The car on the left is a 2004 Indy car (IRL) trying to qualify for the 2004 Indy 500. The car on the right is a 2004 McLaren trying to qualify for almost anything (they haven't had the best of years). The first difference, although not noticable in these pictures, is the fact that the Indy car is running on slicks. The F-1 car has run on grooved tires for quite a few years in an effort to slow them down. That hasn't worked all that well. The next most obvious difference is the rear wing shape. The Indy car has what is called a single element wing. The F-1 cars frequently use a triple element wing. Very tunable for differing track conditions. Aerodynamics is a subtle difference, but the fact that you can see the rear suspension on the Indy car means that the slip stream can see it as well. Same with the rear wing supports. We're only looking at visual differences here. Engine, transmission, computer, brakes and many other differences are huge as well.

In 2002 there were finally races run by Indy cars and F-1 cars at the same track (but on different days). It was Circuit Gilles Villeneuve in Montreal, Canada. The slowest F-1 cars (Minardi) would have out-qualified the fastest Indy cars by 6 seconds per lap for the F-1 race. That's a staggering, huge difference. Minardi itself was about 6 seconds off the pace that year for the F-1 pole position in Canada. So the F-1 pole sitter would have been 12 seconds ahead of the fastest Indy car. Per lap! NO CONTEST.