I was curious, so I did some homework. This site says
there are 8.8 KWh, after conversion inefficiencies, in one gallon of gasoline.
But then, how do you go about converting that into miles traveled? If you just
convert to foot-pounds, you're figuring the energy used to *lift* that
amount of weight, not carry it over essentially a flat surface (ignoring the
mountains in Arizona!). So let's just use a typical 20 mpg for a 3000 pound
vehicle, and extrapolate. 3000 / 170 is about 17.6. Or, I add less than 6
percent to the vehicle's weight. Let's say that translates into 6 percent worse
MPG, so now we're only getting 18.8 MPG. Is that valid? No clue. San Ysidro to
Deming is 630 miles according to Google Maps, so without me the trip would
cost (assuming the other passengers are weightless) 630 / 20 * about $2.50 per
gallon is about $80. With me weighing it down, the total comes to $84. So I
was off by a factor of two or so. Not bad for a wild-assed guess. Yes, there's
still a lot of guesswork in the calculations, but I think my point was valid.
One extra passenger does not add significantly to the fuel expense, because
the vehicle is using the bulk of the available energy to propel itself.

last updated 2013-01-10 20:36:07. served from tektonic.jcomeau.com