 Complete the following phrase:  The first major technological development, Bugattis re-introduction of mid-engined cars following Ferdid Porsches pioneering Auto Unions of the 1930s, occurred with the Type 251, which was unsuccessful. Australian Jack Brabham, world champion during , , and , soon proved the mid-engined designs superiority. By , all regular competitors had switched to mid-engined cars. The Ferguson P99, a four-wheel drive design, was the last front-engined F1 car to enter a world championship race. It was entered in the 