Hi, I have not read all of comments on this page, but in case you are still looking for a workaround to fix it - just read this thread, it offers, very likely, what you need:
Make sure to read till end (2 pages), it helped for some people, (if not for everyone)
Edit:
That video is somewhat outdated, make sure to check these official doc guides as well:
(Optional) If you are new, then read look at “Physics Asset” section there:
http://api.unrealengine.com/latest/INT/Engine/Physics/Vehicles/VehcileContentCreation/index.html
(Important) up-to date vehicle setup guide: