I have a 1997 Jeep Wrangler and the compatibility report mentioned that my Jeep will not communicate fuel consumption, as expected. My primary purpose for potentially buying the product will be to use this app to alter driving habits based on price per trip. How will the app calculate price per trip if actual fuel consumption hence accurate cost per trip? Is there a way, after a period of time, it can average my mpg based a number of datapoints collected after fill ups? Basically, what will be the user experience for cost per trip metrics if I don't have a vehicle that reports fuel consumption back to the device/app?