The 3,600 km figure was achieved with hours to spare, and with peak speeds down the Mulsanne Straight exceeding 140 mph. The overall averages were of 107.8 mph and 6.97 mpg. As the only car in its class it was unplaced, but the same performance by a petrol-engined car would have placed it in 8th place. 1964 For the 1964 season, the major change was the addition of a pair of ceramic rotary regenerators to the gas turbine, so as to improve efficiency. Although often reported as "heat exchangers", these use a different technique. Two honeycomb disks rotate slowly at 20 rpm with both inlet and exhaust airflows passing through them, but separately. This heats the disk, which then rotates, and in turn heats the inlet air. Regenerators slightly restrict the peak power of a gas turbine, but hugely increase its efficiency in compensation. The car also gained a new body, a closed coupe designed by Rover's William Towns. To improve intake airflow, large pods were added over the rear intakes, after the test weekend, where it ran with small air scoops. There was little time to test the new engine however, and the car was also slightly damaged during transport back to Britain. For one of these reasons (history is unclear just which), the team withdrew from the 1964 24 Hours of Le Mans. 1965 Le Mans The 1964 engine was now used to race in anger at the 1965 24 Hours of Le Mans. Rather than running as an "experimental", it was numbered "31" and was a competitor against others in the 2-litre class. The fuel allowance was also now the same as for the piston cars, making the regenerators even more important. Graham Hill and Jackie Stewart were to drive. Allegedly owing to sand from the side of the course being sucked in when Graham Hill ran wide early on, the turbine blades were damaged. The engine began to overheat and for the rest of the race had to be monitored carefully to ensure that the exhaust gas temperature wasn't exceeded. Some hours later, while Stewart was driving, the tip of a turbine blade broke off and damaged one of the regenerators with a massive explosion, although the engine kept on running. The car performed well though, finishing tenth overall, second in the 2-litre prototype class, and the first British car. The average speed was slightly lower