Microsoft continues its battle for the checkered flag with Forza 4, poised to assert its claim as the king of the driving simulator hill once and for all against a growing market of steep competition.

It's been a titanic struggle, and Forza 4 comes out convincingly flexing its technical muscles. Speed is never compromised. No matter how fast, no matter how detailed the environments, the action flows across the screen in a steady stream. It's the constant which, together with the game's well-tuned controls, allows racing fans to lay down just the right line to take a car through a corner on the very edge of grip.

The focus required at such speeds allows little time for sightseeing, but Forza 4's engineers still pushed forward to improve on an already beautiful game. Developer Turn 10's latest boasts the expected upgrade in detail, but it's in motion that Forza 4 really distinguishes itself. Rounding corners in the Alps for instance, sweeping vistas spill out looking more like a distant horizon than a painted in backdrop.

Natural lighting throughout the game convincingly captures the effect of sunlight, sometimes too well. With a bad angle, the glare off the pavement can make it nearly impossible to see the line through a corner. I understand that it's accurate; I'm not sure that it's great for a game, though. And with the work that went into getting the lighting just right, it felt weird that the time of day never changed, no matter how long the race. I also missed night races, and suspect that with the game's upgraded engine they'd be visually impressive. I can't say I similarly missed racing in bad weather.

I play Forza 4 with the assists off, and, as I've found to be the case for every version of the game, it boasts an unrivaled ability to give me the feel of my car fighting for traction on the road. Nevertheless, with the help of data from renowned performance tire manufacturer Pirelli, one of the biggest jumps from Forza 3 to 4 comes in the handling department. Forza 4 delivers an intensely real sense of the tires gripping--or losing grip with--the road and of the car's inertia as it transfers weight through them. Like no racing game I can recall for a long time I found myself relearning how to modulate my angle of attack through a corner with the throttle, and cars responding as I'd expect them too.

Forza 4 really gets across the concept of managing my traction budget. It's straightforward enough in principle. There is a finite amount of grip a car has to split between turning and accelerating/braking; when the combination of the two goes beyond the limit, the car breaks loose. It all hit home as I reaped the benefits of redeveloping the delicate touch necessary for trail braking--starting to turn in to a corner as traction becomes available when trailing off the brakes from the heavy straight-line braking leading up to it.

All of the elements work so well that there's no game I'd rather fire up to go out and run some hot laps at Laguna Seca; however, Forza 4's design seems to be so concerned with 'beating' Gran Turismo at its own game that it became completely married to the traditional structure, and never saw any of the opportunities to move the genre forward from its decade-long rut.

Forza 4's weakness, though, is the ability to produce a good 'race.' In a game that realistically models damage, the reckless abandon with which AI drivers attack is absurd. They plow into each other and me without cause, a habit that carries through the contest. AI issues are far from unique to Forza, neither is its predictable single-player "world tour" mode that regresses alongside its improvements. The way Forza 4 feeds me races for which my current car qualifies makes so much sense; I wonder that it hasn't always been the norm. But there I was at the start of the game in ridiculous three cylinder micro cars, starting a progression through a couple classes comprised of cars that defy the notion of spirited driving.

One of Forza 4's calling cards is its driver-friendly assists, but without any direction whatsoever to the player, how much can those help? Outside of a driving guideline on the track the game offers no guidance on how to go fast. The same applies to modding, part of the game that becomes increasingly important as I got into higher classes. There's a push-button auto-upgrade, but other than selecting it, I'm not involved in the upgrades, nor do I have much of a clue what they're doing for me.

None of Forza 4's issues, though, will amount to even a speed bump for driving enthusiasts. Besides the massive offline "world tour" its online suite includes a smart clubs feature that like its real world counterpart lets drivers get together to share everything from mods to paint and race each other. Challenge leaderboards constantly tempt me to battle for a better position in the game's new "Rivals" mode. I can't turn the game on without giving at least a couple of them a shot. That pull has brought me back every night since getting the game and leads me to believe I have a long future ahead with Forza 4.