Methanol fuel is an alternative biofuel for internal combustion and other engines, either in combination with gasoline or independently. Methanol (CH3OH) is less expensive to produce sustainably than ethanol fuel, although it produces more toxic effects than ethanol and has lower energy density than gasoline. Methanol is safer for the environment than gasoline, it is an anti-freeze, it keeps the engine clean, it has a higher flashpoint in case of fire, and it is the equivalent of super high-octane gasoline in terms of the resulting horsepower. It can readily be used in most modern engines with a simple software setting tweak and occasionally a change in a cheap fuel seal or line. To prevent vapor lock in any possible circumstances due to being a simple, pure fuel, a small percentage of other fuel or certain additives can be included. Methanol (a methyl group linked to a hydroxyl group) may be made from hydrocarbon or renewable resources, in particular natural gas and biomass respectively. It can also be synthesized from CO2 (carbon dioxide) and hydrogen. Methanol fuel is currently used by racing cars in many countries but has not seen widespread use otherwise.