Unlike eliasg who seems to have played both games even before their release , I can't comment on which game will be better.

It's almost guaranteed however that GT5 will outsell forza 3.

and PS3 fanboys...

i made my reasonable predictions...

Wow 2 minutes in and i hate this thread. Forza 3 better graphics than GT5, i don't know, but it think it might be GT5 (DUH).

Why do i feel that people are bashing GT5, because Forza has voice chat, what the hell, i never used voice chat and i couldn't care less about it, all i know is that GT5 will have Top Gear so GT5 pawns (why am i using this word, NOOOOOOO!!!!) forza 3. I haven't seen nothing of Forza 3 and people already claim it will be better than GT5 because they 'played' GT5P. Its just stupid.

Thats my opinion don't bash it, or aren't people allowed to have opinions.

GT5 will sell more.

gt5 of course,they say 1000 vehicles,i can't wait for it

Mario Cart Wii and Motorstorm pacifica(when it arrives) and are both more realistic.
Both provide motion steering much like driving an actual car with a steering wheel -
In Foroza and GT5P you drive a car with thumb sticks ! how can that even be remotely realistic !. Neither of these supposed simulators have even attempted to simulate the standard method of steering a car using a wheel.
I owned a copy of GT4 on the PS2 and it was ok - amazing what they could do with this system but the controls were pathetic and i will never go back to ever using thumbsticks for steering again since playing motorstorm.
I am sure there are plenty of people who will disagree with the above but ->
A real driving or flying simulator should provide both the correct interface and the simulated visual and aural experience - GT5P and Foroza get ZERO points for the interface so while they my do well in other areas like visulas it's negated entirley by the controls.

I really think this thread should be closed until further details are released for both games. At this point any info for either game is purely speculation (aside from the content in GT5P) as no official details have been released for either game.

No your "leaked" details for Forza 3 do not count until confirmed.

Arguing about which game will be better is pointless when we know nothing about either game. We should wait until screenshots, demos, and video trailers are released, then this thread can be reopened.

I don't know about Forza, but for GT you can buy a wheel to play it with... 

Gran Turismo 5 has better graphics, the best gameplay for a racing game and awesome sound thanks to the PS3's 7.1 surround sound system. GT 5 Prologue will still be a better game than Forza 3. GT 5 will have 1000 cars and 100 tracks. Forza 3 will look crappy in graphics, poor sound and meh game play.
^That is my non biased opinion.

Which one was the game you could just drive straight ahead and bump in to walls and still finish the race?

GT5 will be far superior, based on precedent alone.

If Forza 3 is slated to release as soon as I think it will, it will only be a slight improvement over the 2nd iteration.