DriveGain has launched a free iPhone application called CarEconomy that shows your average fuel economy as you drive.

The application can display the fuel economy reading in MPG (US or UK gallons), l/100km, l/100miles or km/l.

CarEconomy does not require user input, you select the vehicle and then drive.

“Many cars in the US, and smaller cars in Europe, do not have a fuel economy meter as standard,” said Simon East, CEO of DriveGain, “Our free CarEconomy application allows users driving these cars to know what kind of fuel economy they are getting.”

CarEconomy works with any petrol (gasoline) or diesel car with a manual (stick-shift) transmission. Support for cars with automatic transmissions will be added shortly.

DriveGain runs on the iPhone 3G, 3GS and 4, iPod Touch (with a GPS Car Kit) and iPad (Wi-Fi + 3G model).

To calculate your fleet fuel costs, come to the Fleet News fuel cost calculator.