Split/Second this week (as if it needed any livening up). The Elite Vehicle Livery Pack adds new liveries for the Brawn, Vixen and Raptor cars and, as a nice bonus, it's free. Meanwhile, the High Octane Supercar Pack adds three new supercars and a new livery for the Ryback Cyclone. The High Octane Supercar DLC isn't free, but it's pretty close, clocking in at 160 MSP or $2 on Xbox Live and PSN, respectively.
Both DLC packs should be available today on Xbox Live, though currently only the Supercar Pack is listed (along with an unannounced Ryback Cyclone Special Edition pack). The Livery and Supercar DLC are slated to hit PSN tomorrow, September 1.