You mean the mini 3D section of
Sonic Jam or the port of
Sonic 3D Blast don't count?

It certainly is odd though especially with the position that Sonic held at the end of the mega drive era. They learned their lesson with Sonic Adventure on Dreamcast but it was sadly too late then. It's still somewhat disappointing that Sega became a third party developer despite it being better for gamers overall. In the mid to late 90s you were either a Sega house or a Nintendo house and playground arguments were had (just some nostalgia from me there

)
My rationale for having them all in cars is that Sonic would very easily win a foot race (Shadow is a pretender) and hence they race in vehicles to make it somewhat fair (although you'd think
Miles Tails or Robotnik would have the advantage due to mechanical skills). For what it's worth I prefer to Sonic and All stars racing games to their Mario Kart equivalent.
Personally I am partial to the heavier/more metal arrangements by Crush 40 but the Sonic R soundtrack certainly did have a 90s charm to it quite unlike anything else in the series.
As for the thread title:
Sonic Heroes - Sega. No prizes for identifying what game it came from