Considering they blocked it off the press builds(attempting to talk to Skystone players will trigger a 'X is not avaliable at this time' just like Vehicle Upgrades), not until release.
Remote Control cars were announced quite a while ago, myskylanders took a pictures of some mock packaging(remember Nitro and Hot Streak, etc etc?) but most people didn't notice it was even there.
Hm,
new interview about the Gamescon build, with a new Activision PR guy. He brought a High Volt figure so if you guys want to see it live, after 2 minutes ish. He also says each vehicle has two sets of mods but considering Hot Streak has 4 I don't know if he counted default and Supercharged.
Traps will give the elemental boost to vehicles even without a villain.
He also kinda implies the old skylanders will be able to use Instant Hot Streak,aww yeah, it's enough confirm for me.
Someone get that guy a cup of water, but he's being so simple with words I'll take it over GB.