GRID was not as much about luck. I loved that game, but agreed physics were terrible compared to GT5. I had a win % of 46% in more than 4500 online races (oh yes, there was some long nights!!).
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To sum it up: (and I have said it all before)
Codemasters: Fun RACING games with half-good physics and a a lot of damage (which is good!). Online is a chaos, it's random and it often encourages people to ram and crash others.
PD: An excellent DRIVING game, with the best PS3 physics and a lot of cars to choose from. The game itself feels rather empty, with the 100%-passive AI and events that makes you able to complete the game with only 2% of the cars in the game and a bad pay-out (atm payout is TOO big though).
Online is too free, not restricted enough, PD should create some more options for pre-determined cars/tyres/limits etc...
Both companies could learn from each other

Both make good games, but Codies makes the largest profit, I think...