These two courses couldn't be more different. London is all about hair-raising slides through tight corners, giving the game a chance to show off just how precise its control system is - each car is solid and realistic to handle, and each one has a unique driving feel. Even controlling it with a pad, you get a strong feeling for the balance and weight of the car; for real car fans, of course, a steering wheel will be the only option.
Daytona, meanwhile, is a showcase for the game's newfound ability to handle 16 cars on the track at once - and for the superbly realistic drafting system, which allows you to speed up in the slipstreams of your rivals by listening for distinct audio cues in the flow of the wind across your vehicle. Yes, they've accurately modelled the wind noise across the bodywork. Come to that, Polyphony has also accurately modelled the engine noise of each vehicle, and the acoustics change depending on which view you're using.
Speaking of views, there's also a new in-car view, which features a perfectly realistic model of the interior of each car, which you can look around while you drive. By the time we were playing around with this feature, we confess that we felt that the obsession with detail had become a bit ridiculous - but we don't doubt that more diehard GT fans than we will adore this kind of extraordinary demonstration of vehicle worship.
One detail we're not sad to see the back of, though, is licences - long the bane of any more casual driving fan who dared cross the threshold of Polyphony's domain. We don't know if they'll return in GT5 proper, but in Prologue, you can load the game and go right into one of the arcade modes or an Event Race challenge (there's a nice selection of these, each with an interesting and challenging set of objectives) without having to successfully stop a car that handles like an angry rhino on a square the size of a paperback book first. Hurrah!
If one failing of GT seems to have disappeared (albeit perhaps not for good) in Prologue, others do remain. Our biggest criticism of GT5 Prologue has to be that the cars are still, after all these years, absolutely invincible - coming away from the most appalling prangs without the slightest scratch to their gorgeously curvaceous and realistic bodywork.
At this stage, GT's stubborn refusal to contemplate a damage system is starting to feel ridiculous. Given the amount of work that has been put into creating the stunning graphics and realistic physics and handling, having cars that bounce off one another without even scraping their paintwork is downright odd. Of course, there are plenty of GT fans who would argue that we're missing the point - if you want a game about crashing, there are plenty of them about. GT is a game about racing.
We'd argue in response that crashing, bumping and grinding is an integral part of racing, and the whole discussion would go in circles until we were forced to admit that we only watch F1 for the crashes and then someone would mention Ayrton Senna and accuse us of being horrible human beings and it would all go a bit wrong. Anyway, the point remains - it's silly that in the most realistic driving game we've ever seen, the cars are invincible. Silly silly silly.
One of the other big appeals of Prologue - and of GT5 itself - is online play. This has long been the holy grail for Gran Turismo, and it's functionality with which Polyphony seems to have struggled for some time. Indeed, it didn't quite make it in Prologue; it wasn't until Christmas Day that it was enabled in a patch for the game, released over the network in Japan.
Sadly, as a result, we haven't been able to get multiplayer working on our test PS3. We can tell you that the game supports up to 16 players online, and that a variety of events (such as races with specific cars and configurations, or online time-trial contests) are available. We also know that Prologue's online functions are rough and ready in some regards, as befits a demo; it's got basic matchmaking functions, but no way of playing against people on your friends list or using in-race chat.
Obviously, this is work in progress (like everything in Prologue) - the My Page screen boasts a section for integration with the yet to be launched PlayStation Home, which strongly suggests that GT5 will have far more advanced multiplayer at some point in future. For now, reports from Japan suggest a solid, lag-free racing experience, but we may have to wait for a European launch for Prologue to give you first-hand details on that. The real news here, of course, is that GT multiplayer is emerging from the mists of vapourware - at last.
We're not sure how keen we are on the idea of paying for a game demo, and there's no question but that Prologue is a demo - the multiplayer is unfinished, the number of tracks and events is limited, and even the game engine itself is clearly a work in progress to some extent. However, we're actually pretty impressed with Prologue. The amount of content you get for your 4500 Yen (about 21 quid) is enough to keep you going for quite a while, and it's not so much a glimpse of the upcoming GT5 as a long, hard look.
For fans of Gran Turismo, then, it's well worth looking forward to the arrival of GT5 Prologue in Europe - and we suspect that for a lot of PS3 owners, this kind of graphical tour de force is exactly what they were hoping for when they bought their console. Whether it can achieve its goal of becoming not only the game, but the media centre of choice for motorsports fans is tough to say at this early stage - but it's clear that Polyphony's next opus is going to be, yet again, a stunning showcase for Sony's hardware, and a bloody good racing game to boot. Look out for Prologue in Europe in the coming months, with any luck - and for GT5, er, some time later.