General Motors has bought a supercomputer from IBM that the companies claim is the fastest in the automotive industry and will more than halve the time it takes to bring a vehicle to market.

Associated Press (AP) said the new supercomputer, based on IBM's Power 4 and Power 5 technology, more than doubles the computing capacity at GM, and is expected to slash the amount of time it takes to get a vehicle to market from 48 months to 18 months.

GM reportedly said that the computer is the fastest in the industry, "by a wide margin," and can compute at a rate of nine teraflops, or nine trillion calculations per second but neither GM nor IBM would say how much the computer cost.

AP said the the technology is expected to allow design modifications and engineering questions in GM vehicles to be handled in a matter of hours when they previously would have taken months to resolve.

A spokesman told AP that GM received the first phase of the supercomputer network in March and will receive a second phase later this year.

Associated Press said the supercomputer is also expected to continue cutting GM's crash test costs by advancing digital simulations - since GM began using the system, it has cut the number of needed crash vehicles, which cost $US500,000 per test, by about 85%.