The Scillian Mafia used to assassinate people with car bombs in the 1990s. The Mafia in and around Montreal also used to car bombs to intimidate and target their enemies. This is obviously a narrow slice of the crime organizations out there but you get the idea, yes, the mob did use car bombs.
Sources:
Davis, Mike (2007). Buda's Wagon: A Brief History of the Car Bomb
Cedilot, Andre et al. (2012). Mafia Inc: The Long, Bloody Reign of Canada's Sicilian Clan
A long mob war in the St. Louis area from the 1960s to early 80s saw literally dozens of car bombings. St. Louis actually had the nickname for a while of "Car Bomb Capitol of the US." Around 4 or 5 of the bombings were later determined to have been from a serial bomber who picked victims at random, but the majority were mob related. They ended in the mid 80s after the FBI got involved. https://news.google.com/newspapers?nid=1955&dat=19811017&id=udgxAAAAIBAJ&sjid=hOQFAAAAIBAJ&pg=2171,4824656&hl=en
http://www.nytimes.com/1981/11/15/us/concern-rises-on-auto-bombings-in-st-louis.html