are you ok with me using 1 mi = 1.6093 km and 3.78541 litres in a gallon as the reference for conversion? Its the best i could find.
Too late, I've done it.
I've tested it with bluetooth and with the touch screen and each time the user changes from imperial to metric or back it converts the units saved to show correct readings with the same config.
http://glengineer.com.au/mpguino_UTFT_v24_Blue.zip
remember to use arduino 1.0.6 when using this code. Its a throw back to the old days.