I noticed the new continent has no roads or rail set aside so it seems ground vehicles are old hat, doomed to the old mainland only, but seeing they don't drive well, no surprise I'd say LIndens have given up on them or having roads is not worth the virtual land wasted but I suspect if a certain percentage of each sim, perhaps 10%-15% was used for protected land/roads/rail/parkland etc, this means more prims per block for the rest of the sim landholders. It's free land, so isn't going to cost LL much more than a few people to design & set it up. But should be all done before the new continent is offered for sale really, too late now of course.
This would spread people apart more rather than this build wall to wall thing that happens in some sims making it possible to have no free ground at all in some sims I suspect.
Entire sims could otherwise becomes more inhabited blocks on the ground with wall to wall houses, no windows (no point) and just roof entires if any entry at all.
I wonder if they realise this also negates future interest from Toyota, Nissan, Chrysler, because if people can't drive their product here, why bother looking at it?