[ODE] Collision against large areas of static geometry

[Stephen Heijster (Stone Lance)]

I'm currently working on a car based game and I have converted my old
collision detection code to use the TriMesh code that is now built into ODE.
My world geometry is organized into tiles of approximately 30mx30m, each
with its own model.

What I am wondering is what is the best/fastest way to do collision against
these geometries?  Should I be creating a single TriMesh geometry for each
tile and then adding them to some QuadSpace, or is it best to merge all the
tiles into one large model and create a single TriMesh geometry?  Does
anyone have any ideas or experience as to which method would be more
efficient?

Thanks,
Stone Lance