75 cycle test, a 200-watt load on the alternator reduces fuel efficiency by 1.7 mpg. Headlights, for example, consume 110 watts on low and up to 240 watts on high. These electrical loads can cause much of the discrepancy between real-world and EPA tests, which only include the electrical loads required to run the engine and basic climate control. Standby. The energy is needed to keep the engine running while it is not providing power to the wheels, i.e., when stopped, coasting or braking. Fuel-efficiency decreases from electrical loads are most pronounced at lower speeds because most electrical loads are constant while engine load increases with speed. So at a lower speed, a higher proportion of engine horsepower is used by electrical loads. Hybrid cars see the greatest effect on fuel-efficiency from electrical loads because of this proportional effect. Fuel economy-boosting technologies Engine-specific technology Other vehicle technologies Future technologies Technologies that may improve fuel efficiency, but are not yet on the market, include: HCCI (Homogeneous Charge Compression Ignition) combustion Scuderi engine Compound engines Two-stroke diesel engines High-efficiency gas turbine engines BMW's Turbosteamer – using the heat from the engine to spin a mini turbine to generate power Vehicle electronic control systems that automatically maintain distances between vehicles on motorways/freeways that reduce ripple back braking, and consequent re-acceleration. Time-optimized piston path, to capture energy from hot gases in the cylinders when they are at their highest temperatures sterling hybrid battery vehicle Many aftermarket consumer products exist that are purported to increase fuel economy; many of these claims have been discredited. In the United States, the Environmental Protection Agency maintains a list of devices that have been tested by independent laboratories and makes the test results available to the public. Fuel economy data reliability The mandatory publication of the fuel consumption by the manufacturer led some to use dubious practices to reach better values in the past. If the test is on a test stand, the vehicle may detect open doors and adapt the engine control. Also when driven according to the test regime, the parameters may adapt automatically. Test laboratories use a "golden car" that is tested in each one to check that each lab produces the same set of measurements for a given drive cycle. Tire pressures and lubricants have to be as recommended by the manufacturer (Higher tire pressures are required on a particular dynamometer type, but this is