I'm a physics professor and I like data that is quantitative and definitive. The Energy panel on my Volt the gives distance traveled (in miles) on a given charge and the energy expended (in kilowatt-hours). Distance is always an integer, but if you take a reading of this display just as the miles counter changes, you can assume an additional significant figure of .0. So, for example, I find that when I go 23.0 miles in my Volt, we consume 8.35 kilowatt-hours of energy, therefore using 0.323 kilowatt-hours per mile. If you convert miles to feet and kilowatt-hours to foot-pounds (which involves multiplying by 502.88), this means that the thrust my Volt is providing is 182.5 pounds. That's how hard you would have to push from behind to get the same performance.

Now the curb weight of a 205 Volt is 3,786 pounds. With three 170 pound passengers (which I had at the time), the net weight is 4,296 pounds. That means that, treating my Volt like a block sliding on a frictional surface, the coefficient of friction is 182.5/4296 = 0.0425. That's the effective friction coefficient of my Volt on a typical trip involving some city and freeway driving on OEM Goodyear tires inflated to 42 pounds.

Before I replace my tires, I would very much like to see similar coefficients of friction from other Volts with other tires. Anyone willing to do the same calculation?