RA2 does use voxels I think as well.
Yes, the vehicles use voxels, and thats about it. buildings, terrain, and infantry use hordes of raster data.
The first time I played the game I thought each vehicle had like 1000 frames, because when they move they conform to the iso terrain. Also, when explosions hit next to them, the vehicles tip as if the blast had nudged them. They look extremely like sprites and I wasn't expecting the game to use something as rare as voxels. It's a really fun game, all iso fans should try it out.