The best way to check consumption is to fill up to the brim from nearly empty. Zero the trip meter. Run the car until nearly empty again, fill to the brim again. Note the mileage on the trip meter. You know exactly how much fuel you've used and exactly how many miles you've done.
that exactly what i do...never had a car where i could rely on the trip computer...always seem way out...but come on guys...we shouldn't be worried about fuel consumption...our only thought is to give our bella's a damn good spanking and then go out and drive our cars hard