Another element of that variety is the motorbikes, and it's here perhaps that PGR4 is less successful. It is too hard to accept the artificial stabilising effects Bizarre has imposed to balance the challenge in car-and-bike cocktail races, and the satisfaction of mastering bikes, borne out by the much better latter examples, where the relationship between acceleration and fast cornering is most rewarding, is still over-shadowed by that need to hold back the onslaught of disbelief. In mixed races, bikes are also rather too easy to defend against or bash out of the way. You need to respect other cars, but you seldom need to respect bikes.
PGR4's greatest flaw though is also one of its oldest. The core racing is still too often reliant on mastering the first half-lap through trial and error and then hunting down the race leader until you are close enough to powerslide caution to the wind and simply barge him out of the way to secure position.
On the one hand, you can't win PGR4's toughest races without being a brilliant player - and the game is undoubtedly extremely good at developing that ability - but on the other, that final stretch of skill is never necessary to locate when you can short-circuit it so mercilessly.
It's particularly galling in a game that succeeds so impressively in serving up convincing opposition. Indeed, the capacity of your fellow road warriors to race rather than simply follow is most apparent because, as you improve, you can actually observe and define the mistakes they are making, rather than having to cobble together a picture of their successes from scratch. (It's certainly a helpful trait from a reviewer's perspective.)
It's doubly a shame, because Bizarre has catered wonderfully to people who do finesse their way into that higher bracket of skill, delivering some truly fiendish Arcade events and even a multiplayer discipline that forces you to use a manual gearbox and the rightly celebrated in-car view on the toughest circuits.
On which note, it's quite probably that conspicuously raw final solution to bypassing the graduation from mid- to high-level skill that has previously punctured the otherwise brilliant multiplayer, which returns here with lots of new ideas.
For a start, it borrows Halo's lobby system successfully, but it's at its best here because, instead of throwing its hands up at the way its game makes people behave, Bizarre has chosen to embrace that. Certain gameplay modes feed on what fans have been doing unofficially since PGR2, while another, Bulldog, is like the best playground chase game ever. In a Ferrari.
Nowhere is Bizarre's devotion to its community clearer than in the game's polish. Fans of the bumper-cam view are blessed with the real speed and rev meters for every single vehicle in the game, while that ability to revisit the old principles has bought the game additional graphical delights, like proper reflections on your bonnet, and even a fair bit of damage modelling.
Another added bauble, Geometry Wars Waves, is a free alternative take on one of Xbox Live Arcade's best games, and available in your very first Career garage. It's ruthless, but brilliant (and seriously threatened getting this review done at all), with Xbox Live leaderboards to bolster its depth.
Geometry Wars is a good preface to discussion of PGR4's Achievements, too, because Retro Evolved's celebrated "Pacifism" finally has an heir - if not half a dozen of them - in the shape of tasks like having to get 8 cars in the air at once, or complete a Hot Lap without touching the brake.
Elsewhere, PGR On Demand does a better job of framing individual achievement better than Gotham TV did in PGR3. Like Halo 3, you can save events and upload them, take photos and do likewise, vote on both and download pretty much everything. A system of tags for each allows you to label your creations so that like-minded gamers can find them. You can even hang photos in your garage, and, like Forza Motorsport 2, there's an accompanying website, www.pgrnations.com, due online at launch so you can obsess over the game at work.
One slight flaw, perhaps, is the decision to award a few gamerpoints for uploading videos and photos, since people will inevitably flood PGR On Demand with gratuitous, dull offerings in order to massage their scores, at least in the short term.
Weighed against the whole, however, it and the game's other minor flaws are forgivable. Freed from the pressures of developing to match a hardware launch, and perhaps steered by the Forza team's strength in simulation, PGR4 wrings the best yet out of an already scintillating arcade racing game. As a swansong for Activision-bound Bizarre Creations, it's more than we could have wished for, and a daunting prospect for whichever developer Microsoft asks to follow it.