Bazza - in a word, no. GP4 kept crashing on my machine and required a driver update for my video card, which not only asked me to configure the GP4 graphics every time, but also transferred the same problem to GP3 and GP3-2000.
Also, from what I've seen reported, GP4 maps some cars without using the whole bitmap, which means that doing a car that's markedly different, (as opposed to updating a Ferrari, for example), may be very difficult.
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