The Triumph TR4A was built between 1965 and 1968 by the Triumph Motor Company in the United Kingdom. The TR4A was an evolution of the TR4, updated with a new chassis. It was hoped the new, but more complex independent rear suspension would address the buying publics' desire for more comfortable riding sports cars. This version has an "IRS" badge on the rear. It has been estimated that 75 percent of TR4A were built with IRS. In 1965 the TR4A IRS sold for just under $2500 in the US. The new suspension eventually proved itself with the buying public and in racing, with three TR4A IRS models posting a team win and finishing 1st, 2nd and 3rd in class at the Sebring 12-hour race of 1966.