Although they failed to win the title in 1967, by the end of the season, the Lotus 49 and the DFV engine were mature enough to make the Lotus team dominant again. However, for 1968 Lotus had lost its exclusive right to use the DFV. The season-opening 1968 South African Grand Prix confirmed Lotus's superiority, with Jim Clark and Graham Hill finishing 1–2. It would be Clark's last win. On 7 April 1968, Clark, one of the most successful and popular drivers of all time, was killed driving a Lotus 48 at Hockenheim in a non-championship Formula Two event. The season saw the introduction of wings as seen previously on various cars, including the Chaparral sports car. Colin Chapman introduced modest front wings and a spoiler on Hill's Lotus 49B at the 1968 Monaco Grand Prix. Graham Hill won the F1 World Championship in 1968 driving the Lotus 49. Around the same time, Chapman moved Lotus to new premises at Hethel in Norfolk. A new factory was built on the site, the former RAF Hethel bomber base, and the old runways were converted into a testing facility. The offices and design studios were based at nearby Ketteringham Hall, which became the headquarters of both Team Lotus and Lotus Cars. Additional car testing was carried out at Snetterton, a few miles from Hethel. In 1969, the team spent a lot of time experimenting with a gas turbine powered car, and, after four wet races in 1968, with four wheel drive. Both were unsuccessful, especially as every race was dry. They penned a revolutionary new car for 1970 – the wedge-shaped Lotus 72. The new Lotus 72 was a very innovative car, featuring torsion bar suspension, hip-mounted radiators, inboard front brakes and an overhanging rear wing. The 72 originally had suspension problems, and Jochen Rindt took a lucky victory in Monaco in the old 49 when Jack Brabham crashed on the last lap while leading. But when antidive and antisquat were designed out of the suspension, the car quickly showed its superiority, and Rindt dominated the championship until he was killed at Monza when a brake shaft broke. Rindt had only recently begun to wear a shoulder harness, but refused to wear crotch straps because he felt they slowed his exit from the car in the event of fire. When the car hit the barrier head-on, Rindt submarined forward and the lap belt inflicted fatal head and neck injuries.