Re: gallons of gas. There&#x27;s the old puzzle: your spouse gets 100MPG in that super-hybrid-mobile. The salesperson wants to upgrade you for $1000 to the super-duper-hybrid-mobile at 200MPG! Double the mileage!<p>You suggest instead that you get the old truck serviced and replace the plugs, distributor and tailpipe. Estimated cost $1000, and should get you from 10MPG to 11MPG. Which is the better deal? Assuming you both drive about 100 miles per week.