I'm genuinely curious. We've established that the Radeon X1 series and prior simply cannot run this game due to shader incompatibility which would suggest that, perhaps, Geforce 6s might be flat-out incompatible too so what's the weakest GPU or CPU or the least RAM/VRAM someone has this game hooked up to?
Check my system specs, It's an old machine but it runs rfactor 2 on all medium and player car detail at high with no AA and a resolution of 1024X768
me, i can run on full setting with no ai car at 8-10 fps Win 7 pro 64 bit AMD Anthlon(tm) 64 X2 Dual Core Processor 4800+ 2.50 GHz, 4.00 GB of RAM Physical Address Extension ATI Radeon HD 4650
Seems like the system requirements were conservative - but not that conservative. The 4650's definitely below min-spec as is the processor.
Playing online with 20-25 cars has better performance then running with 15 AI cars. The AI cars will heavily impact your performance.