Quote:


remember gas miles is something not to thaught as 1 or two miles per gallon but a tenth or twentieth of a mile per gallon compuonded over a year of driving!

I'll come back to this.

Modifying an old car as an MPG project, for the purpose of saving $$, requires some well-planned assumptions and then some calculations.

I have an AHB Dippy that gets around 15-16 mpg mixed driving. I looked at putting in an A500 and assumed it would take me from 15.5 to 18.6 (a 20% increase) and cost $500 (a conservative amount, even if DIY). At 3.85/gal, it would take 12,077 miles to pay itself off. Not bad.

But...
Be aware that the higher your starting MPG, the longer the same mpg increase takes to pay off. Let's take the same $500 and $3.85, going from 15 to 20 mpg has a 7800 mi payoff. That's low-hanging fruit, and would be worthwile. To take the same 5mpg increase, but from 20 to 25, has a 13,000 mile payoff. To get the same 7800-mile payoff requires going from 20mpg to 30!!!

And the higher your base mpg, the more expensive/less return for your modifications.

To be realistic, let's say we can find 3 more MPG (I think planning/expecting to get more than 23 mpg mixed from a boxy M is unrealistic). Going from 20-23 (a more difficult phase of the project) at the same cost/gas price has a 19,900 mile payoff. (and after the OD, I don't think there's another 3 mpg to be had for only $500, so that 19,900 is suspect).

Oh, and going from 15 to 15.1, if you did that for just $50, it would take 29,400 miles for payoff. From 20 to 20.1 takes 52,200 miles.

All food for thought.

Parts I seek: driver doorpanel, 65 Sport Fury, prefer black, needs to be 7-8 on 10 scale, might buy set 16" x 6" Dodge truck wheel(s), from early 70s?, takes 9" dogdish - need for a research job so cheaper is better. 69-73 C-body caliper brackets and/or splashields Send a PM.