But, I got twice that (nearly $12 an hour), at current gas prices
Gallons of Gas Saved per week = 4.05 - 2.29 = 1.76 gallons
Money Saved per week = 1.76 gallons x $3.60 a gallon = $6.34
Extra Time per week = 5 days x (21:56 - 15:30) = 32.167 minutes.
$6.34 saved per week / 32.167 minutes extra time per week =
$0.197 per minute = $11.82 an hour.
Not so sure that's exactly a raise for an engineer, but it's not bad for Bob's own (potentially) free time.
Now the REAL question is how much worse would Bob's mileage be
if he drove the Prius on the
same route as the Echo (3 more miles each day), with the
same speeds (faster, so presumably less MPG), and compare using THOSE numbers. I suspect that comparison might show a much less hourly rate for Bob's time! (It might be less than $6 an hour, then.)
Or Bob could take his 10-mile Prius route, and just drive that 35 miles per hour leg
faster (51 miles per hour?). and maybe
on the freeway (to avoid 2 lights), which would minimize the time difference, yet he'd still get significantly better MPG than in the Echo. This could boost his hourly rate.
I'm sick, I know...