And this is why it's got the rep it does. The fact is, you are just blantantly wrong.
NASCAR is just as much if not MORE technically advanced than F1, although it isn't advertised. American audiences tend to care more about the racing (i.e. swapping paint) than all the flashy lights and cool looking power and torque graphs. So you don't see much tech on TV coverage. But behind the scenes, there is a HUGE amount of cutting edge technology and simulation going on.
One of the things that make it so technically challenging is that by definition, NASCAR tries to wring as much performance and speed as possible out of heavy cars using "new" 30 year-old technology. Do you think getting 850hp out of a carbureted 355ci engine at 9000 rpm's, for 4 continuous hours is easy? (Not to mention the physical and mental stamina required to sit in 120* heat for that long while driving 200mph an inch away from cars on both sides)
BTW - How many world class F1 drivers have tried NASCAR, and won a championship? How many have tried and failed to win a single race, and left the sport with the utmost respect for what it is and what it takes to win? You can get back to us on that if you'd like.
With all of that said, my biggest dissapointment in GT5 is probably (ironically enough) the NASCAR cars, simply because GT5 does nothing but promote an even more negative opinion on the sport due to how poorly they represent it. I've been a fan of NASCAR for 20 years... but GT5 is starting to make me rethink that.