The Koenigsegg CCXR is an "environmentally-friendly" version CCX powered by essentially the same twin-supercharged V8 engine but converted to use E85 ethanol fuel. The engine tune in the CCXR is more powerful than that of the CCX, putting out 759 kilowatts (1004 bhp) at 7200 rpm and 1060 Newton metres of torque at 6100 rpm, 25% more power than the CCX. Christian von Koenigsegg said that "Our engineers couldn't quite believe the figures when we tested the car". The increased power is a result of the cooling properties of ethanol in the engine's combustion chambers allowing for a higher pressure in the cylinder and the biofuel having a higher octane rating of 113 RON compared to 95 RON for petrol in North America and 100 RON for petrol in Europe, although the CCXR burns slightly more fuel than the CCX with 17 Litres per 100 kilometres (15 mpg). The only changes to the engine are modified fuel injectors, upgraded fuel lines and piston rings and a higher boost setting on the superchargers.Koenigsegg stated that CCX owners will be able to have their cars converted to the same engine specification as the CCXR for approximately US$100 000 (€80 000) extra, although the CCX remains available for purchase as biofuel for the CCXR may not be available in some locations.