2007 BMW 6 Series Owner's Manual - Page 201

Fuel specifications Never used leaded gasoline; it will permanently damage the catalytic converter. Do not use E85, i.e. fuel that consists of 85% ethanol, or Flex Fuel. Otherwise permanent damage to the engine and the fuel supply system will result.< Required fuel Super Premium Gasoline/AKI 91 This gasoline is highly recommended. However, you may also use gasoline with less AKI. The minimum AKI rating is 87. If you use gasoline with this minimum AKI rating, the engine may produce knocking sounds when starting at high outside temperatures. This has no affect on the engine life. Do not use gasoline below the specified minimum quality, otherwise engine damage can result.< Use high-quality brands Field experience has demonstrated significant differences in fuel quality: volatility, composition, additives, etc., among gasolines offered for sale in the United States and Canada. Fuels containing up to and including 10% ethanol or other oxygenates with up to 2.8% oxygen by weight, that is, 15% MTBE or 3% methanol plus an equivalent amount of co-solvent, will not void the applicable warranties with respect to defects in materials or workmanship. The use of poor-quality fuels may result in problems relating to drivability and starting, and to a tendency to stall, especially under certain environmental conditions such as high ambient temperature and high altitude. Should you encounter drivability problems which you suspect could be related to the fuel you are using, we recommend that you respond by switching to a recognized high-quality brand such as gasoline that is advertised as Top Tier Detergent Gasoline. Failure to comply with these recommendations may also result in unscheduled maintenance.< 199 Online Edition for Part no. 01 41 0 013 312 - © 02/07 BMW AG Reference Mobility Communications Entertainment Navigation Driving tips Controls At a glance