torque app help

[whostean]

Fellow cheapskates! I require assistance...

I have a 98 Volvo with a faulty speed sensor (one of the many common problems with these cars.) The car has a built in mpg calculator, but this doesn't work due to the car not knowing how fast it's going. Rather than drop the 150 bucks to get it fixed, I thought I could purchase a $13 bluetooth obdII reader to pair with Torque Pro to get an estimate of what the car is doing in real life.

The app works great, except that it too will not calculate the mpg because it doesn't know how fast the vehicle is moving. However, there IS a GPS speedometer option.

My question is: is there a way to force the app to calculate mpg using the GPS, rather than the vehicle speed sensor?

Thank you so much in advance!