Paints and tunes can still be created, traded and used, but painters and tuners are now paid according to usage, not on an initial selling price (which is now effectively at no cost to the purchaser).
There will still be a way to search for community-created tunes and liveries, but not by using the current Storefront system.
It seems like the Auction House has been completely removed because community tunes and liveries are now free to buy, with the game 'paying' the creators based on how much their creations are used by other players.
The game will 'learn' what kind of paints you like and will direct them to you, make suggestions etc.
It was suggested that Drivatar cars (ie AI) will use community paints/liveries.
Oh, and Dan was unsure about existing wheel support, said he wasn't the best man to ask.
Disappointing news about weather and night, but kudos to Turn 10 for being up front about it now.
Edit: not sure how true this is, but it was hinted by Dan that all material shaders used in the game can be used to paint the car, eg full brushed aluminium finish, full carbon finish. Maybe leather cars? Sounds daft.
Edit 2: ALL cars are Autovista now. This possibly/probably means a vastly reduced car roster from FM4.
Part 6 will have weather. Just wait 18 months.
Community tunes and liveries will still exist, but they are free to 'purchase' and use. The creator gets paid (by the game, not by the user) every time they are used.
Storefront & Auction House were pretty much staples of the series. Maybe not enough time to get it working on new tech for launch?
A bit disappointed that there is no night racing, can live without rain and such but night races is gonna be missed.
I'll add this to the OP.
I expected it to be Forza 4.5.
EVERY CAR in the game is autovista.
'You can open everything and look inside etc'.
IGN vid interview around 4'10"
And wtf, you guys misunderstood the no auction house part.
Custom liveries will exist of course, you just won't need to pay for them and AI will use them too. Something ppl have been asking for a while and auction housa had become rather pointless anyway, ppl were misusing it all the time.
If they don't have an auctionhouse or storefront, how could they do this?