Whenever I download them, their OBJ. files don't read with Blender.

So what happened to the mtl. files (Needed to run OBJ. objects in programs like 3D Studio Max and Blender) in his products (I'm talking about his Batmobile, Shelby Cobra and Ford GT40 models)?

Indeed, VK's object files as is do not import into Blender. Two ways around this though, both methods result in a larger object file.

1) Import the obj into UVmapper and save as a new object. Results in a file size of 13M or so.
2) Load into Poser and save as obj with just the final checkbox ticked. Results in a file size of 18.8M.
 
Both methods allow the model to be imported into Blender with grouping and material zones intact. You will have to apply the maps manually in both cases, which you should be able to work out from inside Poser.
 
As to why the original obj doesn't import, I have no idea. Hope that helps.

Touchwood:

Indeed, VK's object files as is do not import into Blender. Two ways around this though, both methods result in a larger object file.

1) Import the obj into UVmapper and save as a new object. Results in a file size of 13M or so.
2) Load into Poser and save as obj with just the final checkbox ticked. Results in a file size of 18.8M.
 
Both methods allow the model to be imported into Blender with grouping and material zones intact. You will have to apply the maps manually in both cases, which you should be able to work out from inside Poser.
 
As to why the original obj doesn't import, I have no idea. Hope that helps.