The crew at ISI have improved the wet weather in F1Challenge. If you have the graphics at 32bit, and the Special effects at High, you will struggle to see in the spray created by several cars going fast. The spray now goes a long way back. One time at Monza I even ran into the back of someone David Coulthard style because I couldn't see. Oops! Luckily though it was a BAR, and not an annoyed German in a bright red car.
They've also changed the handling in the wet. There is now a lot more grip if you're on the right tyres. I think that this however isn't particularly realistic. No way is there that much grip in real life! Watching wet races will show you that the cars suffer massive turn in understeer, and exit oversteer. There's barely any hint of this, even in Monsoon conditions, just an overall slight loss of grip. I'm told that there is a drying line on the track when it stops raining, but as I haven't done a race where it dries out yet, I can't clarify this. The reflections of 'F1 Championship Season 2000' haven't reappeared, so the track looks the same in the wet and the dry. I therefore can't grasp the concept of a drying line.
GP4 is often slated as having 'tin foil' reflections. They can actually be turned down (by turning reflections up actually!), but even the 'tin foil' reflections aren't unrealistic. If you study a soaking wet piece of good tarmac (as I have done many a time, often in my Food tech. lessons!), you'll notice that the reflections are very vivid. The reflections on the track in GP4 are scaled down too the less water there is. A drying line is evident, and if you're on slicks, crucial to stay on. Just putting 1 wheel off the line onto the wet tarmac can leave you spinning towards the detailed scenery.
The handling in the wet in GP4 also appears more accurate, even with the default physics. There is less grip the more rain there is, even on the right tyres. The right tyres, as in F1C, are still crucial. The car is difficult to get into the corner and hard to keep in a straight line coming out. Aquaplaning really is prominent, something missing from F1C.
The texture types in F1C haven't changed from F1 2002 (but they've been improved; see 'Tracks'). There are new skies however, and these really do look the part. I sometimes find it hard not to keep looking at them when racing.
The new car models are fantastic, and are of the highest quality. The liveries finally look realistic out of the box, and the cockpits are also pretty neat. A lot of time and effort has clearly been spent on this area of the game, and it's paid off.
Something has changed somewhere in the graphics engine however. Whilst some people report improvements in their FPS, others report no change and some (like me) report a drop. With exactly the same settings as F1 2002, I suffer about a 10-12FPS drop in the races. This makes the FPS uncomfortably lo (ie from 13FPS to rarely more than 30FPS in the opening laps). The only way I could get a useful gain was to take the 'Other Vehicle's Detail' down to High from Max. The result was a tripling of the FPS, but now the car models look quite bad as soon as they get about 2 car lengths away. This is only in on board cameras. The TV cam for example sees no change with the changing of this setting. I do now get between 25FPS and 60FPS in a dry race, with a slight decrease in the wet. There is still an FPS drop every lap because of the Special effects. I was hoping that they would have sorted this, but no such luck.
The cars now move more convincingly too, and don't float as much. They still seem a bit detached from their environment in their movements, but not as badly as before.
The car models in GP4 are very good, as in F1C. They're not quite up to the standars of F1C though, but the downloadable ones are. GP4's graphics engine is clearly un-optimized. It was GC and Co's first attempt at a fully 3D graphics engine, and it shows. The game is often hard to get working and there are clear problems. Many people suffer inexplicable low performance (as in the case of F1C, but just worse).
The engine is different from just about every other non GPx game. You choose the FPS and they are locked. PO (Processor Occupancy) varies. If the PO goes above 100%, more is happening than the computer can cope with. The result: the game goes into slooooooow motion! This means that people have to have low FPS to avoid this effect (about 120% is when it gets a bit too slow for my liking) I run @ 33FPS with most settings on full in 1280*1074 resolution. People complain about the low FPS, but 33FPS looks far better than 33FPS on any other game. I actually prefer this system, and it's better for people with lower range systems as the game doesn't plummet to an unplayable level. On my old system, the PO in GP4 used to sometimes go up to about 140%. It soon got lower, so I could put up with it. In F1C, the FPS went down to 6 often, causing me to crash. GP4's system just means you can't get excessively high FPS (it can't go higher than 60FPS anyway).
The textures in GP4 are bolder and brighter. People say they look cartoony, but I believe they look better than the slightly washed out textures in EA's series. It's a matter of taste really.
I think that GP4 in TV Cam mode is incredible, and looks very realistic, just like it's on TV. Once again though, this is a matter of personal preference, and you can only judge for yourself. But the cars do look more 'in place' than in F1C.
Unfortunately, GP4 doesn't have some of the, what I call, 'blending' textures of EA games. This is like line fading on the tracks, and where kerbs and gravel meet. In GP4, the kerb and gravel are clearly separate; in F1C the two merge in a dust like effect.