The EPA rating of the Honda FCX Clarity 60 miles per kg hydrogen. Now if you were to
An equivalent car with a internal combustion engine running on methanol would be much less mpg than a gasoline powered engine because there is less energy per gallon in methanol than for gasoline. About 60%, if memory serves.
If an equivalent gas powered car got 30 mpg with gas, then methanol would only be about 18 mpg. In other words, a little more than half of the efficiency of the hydrogen obtained by hydrolysis of methanol. Not to mention that methanol is cheaper than gasoline.