I have seen some leaked information about season 6. I don't want to post the actual images, so I'll just summarise some of what I've seen.
The leak claims the season is going to be Red Bull themed, with one Red Bull themed playlist available at the start of the season, and another added mid-season.
A new plane category, jet, is going to be added.
Some adjustments to gear shifting to balance the competitiveness of different options. The language used in what I've seen isn't completely clear, but I imagine they're trying to make it so people don't need to use 3rd party manual with clutch hacks to do the fastest times.
Summit feats will be traffic free.
New Prestige Ticket Shop content.
Map scenery improvements.
New vehicles - there is a list of claimed new vehicles. No hypercars in the list, but cars from all of rally, drift, plane, racing, monster, motocross, street, alpha gp.
Quite a lot of existing vehicles to get handling updates.