Some info from IGN
March 20, 2008 - We've been playing the Japanese release for some time now in the office, but today we finally managed to score a preview build of the US version of Gran Turismo 5 Prologue. Fans of the series already know that the US release in April will sport a bevy of enhancements over its Japanese brethren, including more cars, tuning options, split-screen racing and more.
If you imported the Japanese version, right from the start you'll notice a few differences here and there throughout the menus. There are more car manufacturers this time around, including some tuner specialists, and things like the events picker has changed (the list goes up and down instead of left and right, has a different skin). And obviously, everything is in English. The newer event selection looks a little nicer, though since I strongly assume it'll look much different in the full Gran Turismo 5, I'm not investing too much love into it.
Starting out with 35,000 credits, I snagged a Ford Focus ST as my first ride. The dealership menu is still rather basic in that you can't search by power or anything of that nature, so you're stuck browsing cars one at a time. So rather than wander through and figure out what the best bang for my buck was, I just picked the first thing that seemed decent enough to warrant my cash. And no, Prologue's Focus doesn't feature Microsoft Sync, so my pleas of "Play artist Disturbed Mutants" toward the screen went unheard.
It could just be in my head, but the driving physics in the US version of Prologue seems to feel slightly heavier while remaining just as responsive as ever, which I dig (true or not). Regardless, the game drives fantastically, of course, and it's an absolute blast to burn around a course.
Speaking of courses, the US release of Prologue includes the High Speed Ring track, which has appeared in almost every previous release of Gran Turismo. So while I won't go into too much detail on its layout or what have you, know that it's still fantastic fun to drive and is just one more reason to pick this up on release day.
Aside from the new rides, perhaps the biggest addition to the US version is the ability to tune your cars. You can only tune, not upgrade, so you can't add on a turbocharger or some such yet (we'll have to wait for GT5 proper for that). The tuning stuff here is reasonably robust, though you'll have to finish each of the events in the C, B and A classes before you're allowed to dive into its options. Once you do, you can tweak the following:
Max Turning Angle
F/R Torque Distribution
Once you've got a setup all lined up, you can save it to one of three slots available for each car. Each setup will result in a performance points score, which is essentially a grade for how fast and agile your car is. This index is used to determine which other cars it can go up against, so if you were to turbocharge your Mustang, you wouldn't be able to race against standard Ponies anymore. However, you can also use this to your advantage and race against weaker rides by intentionally limiting your vehicle's performance. This helps in some restrictive races when you don't want to pick up a low-end ride just for one event.
Unfortunately, the online component of Prologue doesn't work in the build we have, so we won't be able to test that out until sometime closer to its release. However, what we've played so far shows that it's a nice bump over what hit Japan a handful of months back, and we had plenty of fun playing that, so we're psyched for its release come mid-April.