forgot to mention that not much has changed in city sample in vehicles, compared 5.1 content assets, source and plugin so to me this looks like problem with some engine code or settings, thats what i believe but not confirming 
forgot to mention that not much has changed in city sample in vehicles, compared 5.1 content assets, source and plugin so to me this looks like problem with some engine code or settings, thats what i believe but not confirming