Via Xbox.com, article by Ryan Treit: 

Through Rain, and Sleet, and Snow
The recently announced weather system for Project Gotham Racing 4 is a radical shift for the racing genre. It's a superior technical achievement to marry thunderstorms and snow-packed roads with the raw speed and visual detail of the Project Gotham series, and its effect on gameplay effect is just as amazing.

Power-sliding a Ferrari Enzo around a tight icy turn, hurtling down the home stretch through the driving rain in a throaty Mustang, and zig-zagging around puddles in a TVR Sagaris are all unique and thrilling gaming experiences.

Whether you're racing in hot, sticky weather with an overcast sky, in a dense fog in a drizzling rain, the icy cold on a crisp, clear day, or in a raging thunderstorm, the combinations are varied, unpredictable, and most impressive, as the conditions even shift and adjust in real-time during a race.

Two Wheels Are Just as Good as Four
The weather system was the shocking pre-E3 revelation, but the absolute E3 show-stopper is that motorcycles will now be included in the game.

That's right, racing bikes have made the cut in Project Gotham Racing 4 and they help revitalize the franchise with a feel and control all their own. From wheelies to endos, these lightning-quick and nimble machines provide a refreshing change of pace. If you thought the white-knuckle sense of speed was intense before, wait until you rocket down the home stretch on two wheels instead of four.

Even better, the racing bikes compete right alongside the cars, so you don't have to compartmentalize your racing.

Team Play Online
With Project Gotham Racing 4 comes a commitment from Microsoft and Bizarre Creations to foster a more active and competitive community, and the new Team Play concept helps cement that wish. While you can still race in the classic "every man for himself" mode, you can also team up with friends and take on rival teams.

Finishing first may still be important, but the overall success of the team takes top priority, and with that single shift in mindset comes a world of new racing tactics. Block opponents and allow teammates to pass unhindered, then drift behind your buddies, calling out opposition locations. Working together as a cohesive unit instead of just being a lone renegade on the track can be a lot of fun.

Meet the Icons
The stable of available vehicles in the Project Gotham series has always leaned heavily towards high-end exotics, but with PGR4 you'll find a new breed of cars with an even higher degree of rarity. Iconic cars from generations gone by are now available, and while details on exact models are scarce, we do know that everyone's favorite Back to the Future transport—the DeLorean—makes an appearance.

On Demand
Project Gotham TV was a much heralded feature in PGR3, and it's been retooled from the ground up for the newest entry in the series. The new system—now known as Project Gotham On Demand—focuses on highlighting the spectacular feats of friends and competitors. From toggling through uploaded photos of their favorite moments to streaming a video of their latest victory, On Demand delivers nearly instant access to content you want to see from the players you actually care about.

News and Notes
In addition to the more radical upgrades, our few minutes of preview time with PGR4 uncovered some other lovely tidbits:

• Cityscapes: Three brand new metropolises have been given the next-gen treatment for PGR4. Shanghai, Quebec, and St. Petersburg are all in the game, keeping with the series' penchant for exotic, gorgeous locales.
• Shudder speed: The camera now shakes and shudders when you begin driving well in excess of 100 mph, further defining the line between going fast enough to make you smile, and so fast you cut off the circulation in your hands from gripping the controller too tight.
• Friendlier angles: While the courses are still technically demanding, you'll find most turns a bit more generous and conducive to the power-sliding mayhem the Project Gotham series has always encouraged.
• A.I. for Kudos: The A.I. now races more for Kudos and less for the best possible time. In short, you won't spot the reactive A.I. taking the same perfect line through every lap like in years past.

Project Gotham Racing 4 is shaping up well beyond the evolution of a standard sequel. Where PGR3 introduced us to Xbox 360, PGR4 looks to put the technology through its paces now that Bizarre Creations understands its full capabilities. Look forward to more coverage on this title throughout E3, and in the months leading up to its release.

Tip thanks to J. Alexander Bill, the creator of Post-Its.