The Dreamcast version of Sega Rally 2 has quite the history, and it's a subject I've always been interested in...
My understanding is that Sega was under obligation to develop at least one of its first party Dreamcast launch titles using Windows CE in return for Microsoft providing the console's secondary operating system, with members of the same CS Team that had previously worked on Virtua Racing Deluxe, Saturn Sega Rally and Daytona USA (Championship) Circuit Edition tasked with converting Sega Rally 2. At first, this division had been intending to release its home treatment of SR2 for the Dreamcast and PC simultaneously, with the earliest build seen at the Tokyo Game Show '98 Autumn and on the Dreamcast Promotion Disk. Still being shown in non-playable form just weeks before its planned arrival, management at Sega listened to public concerns and decided to massively delay the end product, even making the decision to bring in staff from AM Annex, who chose to concentrate on finishing the Dreamcast edition first, even though it remained based on the PC code base rather than being a more direct Model 3 port.
From what I've read about the period after AM Annex came on board, staff had less than two months to recreate SR2 almost from scratch, and I seem to recall one of the programmers mentioning that he worked eighteen hours a day, sleeping under his office desk in order to ensure the game made its rescheduled late January '99 deadline. Although the end product is close enough and packed with additional content, including several new tracks that were supposedly leftovers from the arcade original (though not the forest stage most prominently seen in location test builds and subsequent print magazine previews), it was noted for suffering with an uncapped frame rate that was anything but consistent, frequently slowing down whenever you'd try navigating a turn. Thankfully, there are locked 30 and 60 fps - or 25 and 50 in the unoptimised PAL edition - modes that can be enabled on the title screen, the latter achieved by reducing trackside detail to bring this overall package even further away from its Model 3 Step 2.0 source.
Despite its many problems, I still really like SR2DC, even if I'd have preferred this to have become the first online-enabled game here in Europe as opposed to the relatively lightweight Chu Chu Rocket. I can't say much about its PC counterpart, because I've not had a system capable of running this in quite a while - for some reason, my current setup is plagued with compatibility issues, tough I remember it being virtually identical to its console equivalent, which is little surprise when you consider its roots. Beyond some minor remaining graphical inaccuracies and the internal refresh rate being a little higher than on real hardware, I'd suggest that the Supermodel emulator is now the best way to experience SR2, providing you have the necessary power to run it at full speed.
P.S. Since I'm apparently writing love letters to my favourite racers from the late '90s, I feel that Sega Touring Car is long overdue a reappraisal!