>>43369499Vehicles, sure. Miniatures of vehicles, rarely; and then it really depends on the campaign. I ran a Rogue Trader campaign that used Battlefleet Gothic miniatures for ship combat. It helped to keep track of things when terrain was sparse, as it frequently is in space. Most personal combat was purely roleplayed, though, and vehicles factored in only rarely.
In the last seven years, I can think of only really three complex vehicular encounters. The first was in a very early Dark Heresy campaign and involved a Salamander scout vehicle, which we spent the session fighting from and eventually used to run down a Chaos Space Marine (we lost it when we failed to kill him and he ripped through the undercarriage); the second, a Rogue Trader campaign in which we flew a Vendetta gunship and executed a series of borderline impossible aerobatic maneuvers while attacking indigenous, post-apocalyptic human natives squatting an archæotech arcology; and the third, same campaign, when the party was split and the two most irresponsible players dueled a sandworm with their Taurox. They lost the Taurox. And the NPC mooks that were accompanying them.