Making any claims of how well one did against another on a road course is no where near a legitimate comparison, unless the persons racing against you were high caliber race drivers. Just cause a car may make over 400hp, that doesn't mean the driver is in tact with the cars ability.
Speaking from experience racing on Road Courses/AutoX's/Drag Strips, it's a Drivers Field, especially for the first 2. Take the best driver put him in a mediocre performance machine then put an average driver in a high powered machine and chances are the driver with more experience will still win. I won't go into my personal experiences but when comments are made that "I drove so fast onto the rear of a high powered car that I drove that racer right off the race track," obviously the caliber of Drivers needs to be raised, because I can tell you, you would never be able to run me off the track, better yet have fun trying to stick with me!!!
I side with Dan Nixon's comment, in MOST cases, especially on a fast road course, with 2 very good drivers in both either a High Powered Camaro/Mustang or Corvette against a Contour, the Contour should almost always get it's A** handed to it, almost always, though I have stepped cross that line already (though my SVT is very highly modded for track conditions)