Don't think this has been mentioned in this thread yet, but I was just writing about it for a drafting and design project I'm doing on RMC trains, so I thought I'd mention it.
RMC stated in an interview earlier this year that new trains were in the works and that Timbers and Vengeance would both have them.
@Hyde noted that it probably wouldn't be much of a difference, however, I did notice something in both renderings that is different from the others.
Original train design for comparison.
You can see very clearly in a few spots that the zero car seems to be articulated differently and features two runner wheels instead of one. Looking back, it appears that every row now features two runner wheels. There seem to be two steel rods running from the front of the first car to the zero car.
The Planet Coaster rendering shows the changes very clearly.
Look closely in this one and you can see that the official rendering sports two wheels as well.
Twisted Timbers sports two wheels in each assembly as well! Can't see the rods but they might just be covered by the theming, unless Vengeance's are theming, which I doubt.
Let's also not forget that the Gerst trains RMCs used to run had two runner wheels per assembly instead of one. Maybe this handled the track better or something?