http://www.jeux-france.com/news21453_gc-video-gran-turismo-5-prologue.html

 the video is long to download ...

from what I have seen so far :

no car dammage ? (I dont care)
no car penality when there is contact (bad)
good intra-car view
the view in the mirror (dont know the name) is quite bad
IA seems better (others cars try some move to increase their rank)

no car penality when there is contact.

Very very very very good.

Thats the most annoying part of forza.

Or the best. Depending on your perspective.

+1 for ckmlb ...

They tried to implement the 5 second penalty thing in GT4, in the Special/Rally races, but it was just annoying and illogical. If they don't want to spend a month programming it, I'd rather they leave it out and focus on more important aspects of gameplay.
Also, the damage part was never really something I missed even though it would be cool to see how they'd do it at Polyphony!
I think there's just too many cars for damage in these games, I mean; who wants to program individual collison detection and rendering for 700-800 cars?!

I m ok for the dammage on car
BUT
speed penality like (80% power engine only after a crash for example) would have been great to keep people away from using "contact car" during a race. This is the main purpose :
make people learn how to play without enter in contact with others cars.

imagine hat wil happen online if they dont do this ?
u will have last player that will crush, at full speed, on the othes players during the 1st turn...

Nah... definitely I'm not impressed. Cars looks cool but it's not enough. I want nice backgrounds. Trees looks like from PS1... I don't now they should try harder. It looks like DIRT. Nothing more.

No penalty and no crash modelling means you can just ram your way to the front of the pack. True simulation of racing means that if you have the "line" or "position", the other driver has to yeild. If a driver (in real life) forces into a place where he/she doesn't have the right of way, they can be penalized time, points, or disqualified. I'd like my racer to do the same personally. I don't like "arcade" racers any more. I used to love Sega Rally and I'm hoping that their next installment wins me over but after having played Forza 2 and seeing how close to a real racing situation they have taken it, it's difficult to go back to games without those features. Just my .02. Keep the change.

The video is too small to really tell anything conclusive but it looks pretty smooth framerate-wise which to me is the single most important thing.  There were a few moments during the slides and spins that it seemed to kind of jump, but I'm sure thats the quality of the video and not the game itself.

It looks like exactly the same driver AI from the last two games.

And I'm sorry, but contact penalty = lose, especially when mixed with poor AI.  No matter how carefully you drive, the AI often seems hell bent on bumping you, causing you to receive a penalty through no fault of your own.  If the game can't accurately simulate your opponents' driving, then it shouldn't attempt to shoehorn in contact penalties.

 well GT5 Prologue is free so its your chance to decide.