It looks like it's running at a slower frame rate because the sudden changes make 30fps look like it's stuttering, kinda like Sega Rally 2 on DC.
And Burnout has nothing to do with this, it's totally different engines, doing totally different things. Car models aside (obviously much more detailed here) world racing's engine is more similar to that of a flight sim; you don't have a track with a few elements thrown at both sides of the road, you have these huge maps and the possibility to drive everywhere within them.
You can drive around for minutes, then climb the tallest mountain and once on the top, being able to turn back and still see the roads you've been driving on several minutes before stretching below, thanks to its impressive draw distance.
Quite impressive actually.