The main difference betwen the TR4 and TR4A was the inclusion of Indipendant Rear Suspension (IRS). The IRS design used in the TR4A was the basis for the IRS used in TR5, TR6, Sedans and Stag
The TR4 with a dramatically new shape styled by Michelotti, was released in 1961. Its engine is slightly larger than the tr3 at 2138cc, but was still rated at 100bhp at 4700rpm. In 1965, the TR4A was introduced with its main feature being independent rear suspension and engine output of 104bhp.