Frustrated on torque calculations

I hope you folks can help me out here, I had a set of formulas to calculate motor torque requirements.
I did a few examples and the results seemed way to low, for example a torque of 30 in/lbs to drive a 300 pound machine at 10 MPH, seemed ridiculously low.
I have asked around a bit and have no definitive answers as yet.
Does anyone here have formulas that are more or less correct?
Thanks Ryan

Your best bet is to invest in the Drive Train Simulator made by Enigma. You\'ll be able to view all this data while you simulate driving conditions. www.enigmaindustries.com/EDTSim.htm

I looked at it and downloaded the demo to play with
Thanks Ryan