Still is Grand Prix 4, 12 years after the release. The reason is simple - while it had its fair share of bugs and defects, it's the only game that ever came anywhere close to believably represent a F1 race. What made the difference with every other game before and since is the way the AI drivers and cars were managed. Essentially, the game simulated a F1 race in which the player could take part, is so they wished. Every single CPU-controlled car was subject to the same physics rules as the player car, to the point that an AI driver and a human driver could share the same car (as it happened in the hot-seat multiplayer mode) and it was possible to just watch a race unfold - select no driver and the AI contested the race all by itself, with the user able to "ride on board" with any AI driver and watch it drive. As a result, the racing was quite consistent across the different tracks and track sectors - no absurdities like those in the F1 201X series, where you may have the same overall lap time as an AI driver but be 1 second faster in S1, 1 second faster in S2 and 2 seconds slower in S3. The AI drivers were quite convincing too - jostling for positions, making mistakes, diving for gaps when it counted. Very advanced for the time, although there were some flaws during practice and qualifying sessions - sometimes, you'd slow down to allow an AI car through and they'd just slow down with you and sit on your tail until you almost stopped; they also had the characteristic of belting it around the track all the time - no matter if they were on a timed lap or just left the pits - although the AI in F1 201X seems to be the exact opposite, always happy to run into your back and always pottering around the track during practice and qualifying, almost as if they were just there as an obstacle for the player to get through.