I'm not a programmer, but I think getting several cars on the track to think and react seperately would be pretty darn hard.
In my opinion the REAL problem here is perception. What everyone seems to be forgetting is...this is really as accurate as real life! Everyone who's slamming this game because it's "too easy" is looking at it negatively and I don't know why. The reality is...it's just like life with respect to the cars. The AI's cars are base cars...non-tweaked. I think the only way Sony could fix this would be to have difficulty settings for either the game or each race with respect to tunning...OR better yet have an auto sensing AI that detects the level of tunning in YOUR car and matches the AI's cars to yours. BUT I assure you...the representation is real. A GT-R with a Stage 3 turbo is going to kick the livin' sh*& out of a base Beetle etc. That's true in real life too!!! Highly tuned cars are going to crush cars that aren't!!!!!!!!
If you want a challenge...preview the race to see what the competition is and race a comparable base car to them(and LM vs. LM's)....OR...take a lesser car that has been tuned and race against them...(like a 350Z tuned vs. the LM racers)...This is why I love the Polophony Digital race...only "regular cars" are allowed and in that race it's on!
If you look at it correctly...it's very realisitc.
You don't have to use a "slower car to get a challenge"...you just have to use a fair one FOR that particular challenge.
Face it...using a tuned Zonda against a bunch of base RX-7 isn't a fair fight...and the game represents that FACT of life.
J.