Xboxic managed to get some new info for Project Gotham Racing 4, taken from the May edition of OXM magazine:

Enhanced Weather Simulation: “One of the slickest new features in PGR is its weather. Bizarre’s using what it likes to call ‘extreme weather’ for more than just making the sky gray. Water beads up on beautifully on all the gorgeous paintjobs, spray jets out from the tires, and in the in-car view, wipers move and windshields ice up.”
Enhanced Raceway Environments: “A TV-style intro sets up each event, with a commentator offering wisdom…Choppers buzz overhead, camera crews and video vans are everywhere, and hordes of fans line the track. They’ll wear gear with your logo, wave your national flag, and react far more obviously to your performance.”
Extended Car Selection: “PGR4 will deliver a much broader set of vehicles, ranging from a vintage’63 Corvette Sting Ray and the ’54 Maserati 250F to the sleek, ultra-modern Ferrari 599 GTB Fiorano.”
On the tracks: “You won’t want to miss out on your viewing time with PGR4’s tracks, which tally up to 200-plus in 10 locations.”
On Xbox Live initiatives: “PGR4’s cooking up a mysterious new matchmaking system (like Halo 2’s).”
On in-car view: ” Bizarre has two key improvements in the works.You’ll now see drivers moving more- feeding the wheel as they zip through turns or pumping their fist after a win. Special effects will also crank up the tension in key moments: you’ll get a shake effect at high speeds, and your vision will blur after spending some quality time with a a wall.”
In conclusion: “PGR4 feels hugely promising- like a proper sequel with loads of cool new toys.”