moving a vehicle may be summarized as follows: Engine efficiency (20–30%),rm which varies with engine type, the mass of the automobile and its load, and engine speed (usually measured in RPM). Aerodynamic drag force, which increases roughly by the square of the car's speed, but notes that drag power goes by the cube of the car's speed. Rolling friction. Braking, although regenerative braking captures some of the energy that would otherwise be lost. Losses in the transmission. Manual transmissions can be up to 94% efficient whereas older automatic transmissions may be as low as 70% efficient Automated manual transmissions, which have the same mechanical internals as conventional manual transmissions, will give the same efficiency as a pure manual gearbox plus the added bonus of intelligence selecting optimal shifting points, and/or automated clutch control but manual shifting, as with older semi-automatic transmissions. Air conditioning. The power required for the engine to turn the compressor decreases the fuel-efficiency, though only when in use. This may be offset by the reduced drag of the vehicle compared with driving with the windows down. The efficiency of AC systems gradually deteriorates due to dirty filters etc.; regular maintenance prevents this. The extra mass of the air conditioning system will cause a slight increase in fuel consumption. Power steering. The older hydraulic power steering systems are powered by a hydraulic pump constantly engaged to the engine. Power assistance required for steering is inversely proportional to the vehicle speed so the constant load on the engine from a hydraulic pump reduces fuel efficiency. More modern designs improve fuel efficiency by only activating the power assistance when needed; this is done by using either direct electrical power steering assistance or an electrically powered hydraulic pump. Cooling. The older cooling systems used a constantly engaged mechanical fan to draw air through the radiator at a rate directly related to the engine speed. This constant load reduces efficiency. More modern systems use electrical fans to draw additional air through the radiator when extra cooling is required. Electrical systems. Headlights, battery charging, active suspension, circulating fans, defrosters, media systems, speakers, and other electronics can also significantly increase fuel consumption, as the energy to power these devices causes an increased load on the alternator. Since alternators are commonly only 40–60% efficient, the added load from electronics on the engine can be as high as at any speed including idle. In the FTP