Ubisoft's The Crew [official site] is an MMO-y sort of a racer, and its first expansion is suitably MMO-y. Wild Run arrived last night with trucks and motorbikes and challenges and other new things for folks who pay, but its launch also updates the base game with new things for everyone. New lighting and a new weather system are among updates for all. The game's timed demo is updated to show off expansion stuff too. It's MMO-priced as well, with the expansion running you, er, £25 - the same as the main game.
Wild Run's main additions are motorbikes, dragsters, drift cars, and monster trucks, along with a new set of challenges called The Summit. It's a big, fancy, regular event players will need to qualify for, leading to a monthly Summit Finale where they'll race across all sorts of places for glory prizes and glory and whatnot. Players can set their own races for their pals, too. Also, other stuff.
As for the free update for all, that's detailed in there here patch notes. You'll find a new weather system, Wild Run's prologue to lure you in with tastes of the new vehicles, and other stuff.
The Crew's two-hour timed demo is updated too, letting folks have a go on new vehicles as they lark about in solo and co-o and all that.
Wild Run will run you £25 on Steam and uPlay Shop and all that. It's £40 to get the base game and expansion together, though. The demo's up on Steam or, if you want to go through the uPlay app (yes, yes, I know how much you adore it, stop going on about it) it's lurking in the 'free games' section there.