In 1969, Miles had to develop the Lotus 63 4WD car while World Champion
Graham Hill and
Jochen Rindt refused to drive this design, considering it a death trap. In five GPs, Miles finished only once, in tenth place. In between, the car was given twice to
Mario Andretti, but he did not finish either. Miles did qualify mid-grid for the Canadian GP at Mosport, where the difficult combination of fast sweeping bends suited the 4-wheel-drive Lotus 63, which was a 'disaster' on twisty tracks. After Graham Hill had broken his legs in late 1969, he did not return to Team Lotus, driving Lotus cars for the
Rob Walker Racing Team instead. Miles was promoted to number two Lotus F1 driver behind Jochen Rindt for the
1970 Formula One season. In the
1970 South African Grand Prix, where a total of five Lotus cars were entered, he finished fifth in a Lotus 49 with Hill behind him. Miles had driven most of the race with petrol leaking over him, but
Colin Chapman expressed dissatisfaction he had not taken Beltoise for fourth. For the Spanish GP, the new
Lotus 72 was entered, but Miles failed to qualify for the race in which Rindt had to retire early. Due to the problems with the 72, the updated Lotus 49C was used in Monaco, with Miles driving a few practice laps in the 72, and failing to qualify in the 49C. Graham Hill was slower in practice, but had a guaranteed grid place as a past World Champion, and was allocated Miles's 49C for the race, which was won by Rindt. In Belgium, Miles raced the 72, while Rindt relied on the old 49C, and both had to retire. In Zandvoort, the 72 finally proved to be competitive, with Rindt qualifying on pole and winning, while Miles qualified and finished seventh in the race, driving a more experimental and difficult, version of the 72, which retained much of Chapman's anti-squat and anti-dive roadholding features, and was a handful, if having excellent brakes. Miles made an excellent start, jumping into fifth and was running in the opening laps with eight of the greatest GP drivers nose to tail, held behind by good line, brakes and skilful blocking or the luck of a tyro in auto sport. Regazzoni got past when Miles missed a gear on lap 6 and
Piers Courage passed Miles on lap 12. After that an intense midfield duel developed as Miles fought to hold off Jean-Pierre Beltoise and
John Surtees. Rindt required real skill to lap the trio threading through on laps 30–33, ultimately just flagged past by his teammate. Beltoise was not able to get the Matra past the deep braking Miles's 72 until the slippery lap 49, Surtees also got past on the lap, but was immediately retaken by the Miles 72 and Surtees did not finally secure the 6th place point, until he got past four laps from the flag with the 72's brakes effectively gone. In France, Rindt won again in the 72 despite an injury, while Miles finished outside the points once again, although on the same lap as his team leader. By now, it was evident that Miles was thoroughly overshadowed by his team leader who won five races to earn the F1 World Championship that year. According to Miles, Chapman regarded him 'as a sort of grease monkey' and paid him a mere 300 pounds per race, A qualified mechanical engineer, Miles later made a name for himself working for Lotus's road car division. He wrote a column, "Miles Behind The Wheel", for
Autocar magazine, giving his road impressions of sportier cars. ==Personal life==