Even if the T25 wasn't hefty in previous iterations, it has been put on diet. The construction, dubbed iStream, has been redesigned, and the result is a 550 kg/1212 lb curb weight: a 80kg/176 lb drop, or the weight of an engineer. Earlier composite panels have been discarded in favor of carbon fiber, and everything from the seats to the wiring has been rethought to make the vehicle lighter. In addition to reportedly using the lightest available powerplant, a three-cylinder Smart car gasoline engine, the unit has been overhauled by ex-Honda F1 engine wizard Osamu Goto's Geo Technology to minimize friction and maximize efficiency. Shell's responsibility has been to create special lubricants for the car to reach those goals. The vehicle's aerodynamics have also been greatly improved, as the drag coefficient has dropped to 0.29 from 0.37.
Earlier, the T25 was reported to return 80 mpg during testing. The new version can reach 89 mpg when driving along at a consistent 45 mph. The tests performed at the Millbrook proving ground in the UK report an efficiency improvement of 5 percent. Despite its minuscule size, it can still accommodate three people, including a full-size driver who sits in the middle. Murray is 6-foot-6, and it makes sense for him to design a car that he can drive himself.