Is there a software update to display instantaneous MPG over 40 by the trip computer ? I have a April 14 Reg Class E and it does not show above 40 mpg even in a motorway! I drove a Volvo earlier and along with the speed, the instantaneous MPG display enabled deciding optimum speed to drive. I am really surprised by this limitation which is a big let down ! An old 2001 Volvo was better?