Forgeworld just came out with some new units, including the Deimos pattern Vindicator, which Chaos Space Marines have access to as a Heavy Support choice:
Not only is this vehicle strong against vehicles, but it can perform like a long-range, 3-shot, vehicle based sniper, with 88% accuracy per shot and wounding almost anything in the game (except Wraithknights/Lords) on a 2+, with no Armor saves allowed. Put another way, think of this as a vehicle based Vindicare Assassin with slightly less range and BS, but cheaper, more versatile, and with 3 shots a turn, vice only one.
Since CSM generally lack effective long-range fire support (Obliterators and Havocs aside), I think the Deimos Vindicator (or even a pair of them… there is no Relic Vehicle rule like with Sicaran Predators) could be an excellent addition to a competitive Chaos Space Marine task force. Take two Deimos Vindicators, place them on a Skyshield Landing Pad for a 4++ save (doubling their survivability against shooting), and punch out 6 x S9 AP1 Ordnance shots at BS4 (twin-linked) a turn… this should provide an excellent firebase to support the maneuver of the rest of your Traitor Marines on the battlefield.