The TVR Speed Six was the name of a naturally aspirated straight-6 engine manufactured from 1999 to 2007 by British car manufacturer TVR, and used in several of their cars including the Tuscan, Cerbera, Tamora, T350, Sagaris and Typhon.

The inline-six engine is a piston engine with six cylinders arranged in a straight line along the crankshaft. A straight-six engine has perfect primary and secondary engine balance, resulting in fewer vibrations than other designs of six or fewer cylinders.