A fuel economy riddle...with a moral to the story

[Christ]

OP -

This forum, like many others, will NEVER give you a straight answer to a question like this. There are too many points for discussion and fervent outbursts (that others might not even notice) for this thread to have gone any other way.

Just thought you should know that so you don't get frustrated when this keeps happening... LOL.

[chuckm]

Originally Posted by ShadeTreeMech

A married couple have 2 vehicles, both powered by gas.

The husband has an antique truck that gets 10 mpg.

The wife has a hyper fuel efficient car of the future that gets 100 mpg.

Both drive the same 12,000 miles per year.

They both need to cut back on fuel costs, so they go to a mechanic to ask him to help them save some fuel.

The husband is told that if he cleans the crud from bird droppings off his roof and inflates his tires to recommended PSi instead of being nearly flat, he will get 11 mpg from his truck.

The wife takes her vehicle to the dealer and the dealer says they have a hyper efficient chrome plated caneuter valve that will double her mileage so she gets 200 MPG!!!

Who will save more money?

This is a perfect example of why the gallons per mile metric is better than the miles per gallon. Of course, the math is correct either way you do it, but our mind more easily grasps the actual improvement when we look at the gallons per mile figure...
10 -> 11 mpg = 0.1 -> 0.09 gpm
100 -> 200 mpg = 0.01 -> 0.005 gpm
Answering the question of which gain is bigger is much more intuitive when you use gpm.

[jamesqf]

Originally Posted by Christ

This forum, like many others, will NEVER give you a straight answer to a question like this.

Of course not, because it's a loaded "Have you stopped beating your spouse?" question, for which any straight answer you give is wrong. (OK, unless you actually HAVE been beating your spouse :-))

The correct answer, of course, would be for the husband to junk his pickup in favor of one that got halfway decent mpg. Used '80s Toyota 4WDs can be had for $2-3K, and will get over 25 mpg driven in working conditions.

[VegasDude]

Originally Posted by dcb

not sure you did that right. it isn't at all obvious when fuel is in the denominator so lets flip it.

in your scenario car A(10mpg) gets .1 gpm (gallons/mile)
and car B(20mpg) gets .05 gpm.

so @ 10k miles a year they would use 1000 and 500 gallons respectively.

so 2% of that would be ~20 gallons and 10 gallons respectively "saved per year".

I gotta decimal point wrong....

[ShadeTreeMech]

LOL everyone saw through it all pretty quick.

I suppose the moral is that small MPG increases in a larger car are to be preferred to large mpg increases in the smaller car.

The car manufacturers have it all wrong in how they try to boost their fleet economy. Instead of making the big vehicles get better economy, they take a 1.5L small sedan and add an electric motor and battery pack and make it even more economical. Why not do that with their pickups? Or their minivans?

If a family has 2 vehicles seeing similar miles, but 1 is getting much worse economy, the focus should be to get the 10 mpg truck up 5 mpg rather than to get the 40 mpg car to 50 mpg. Sure, a smaller car gets much better mileage, but you can't haul 4x8 sheets of plywood in the back of the Metro. (well, not easily :P)

[dcb]

Originally Posted by ShadeTreeMech

I suppose the moral is that small MPG increases in a larger car are to be preferred to large mpg increases in the smaller car.

lol, I was afraid that was the "moral" Really there isn't a comparison though. If you've sucked it up and got a small car more power to ya, if you are stuck with what you have then make the most of it.

Originally Posted by ShadeTreeMech

Sure, a smaller car gets much better mileage, but you can't haul 4x8 sheets of plywood in the back of the Metro. (well, not easily :P)

Just FYI, I have a $200 4x8 trailer that can, easily, and can still get 45mpg behind my saturn. Seen metros & diesel rabbits with tow hitches too. If I kept this setup vs a larger vehicle that gets 22.5 mpg, I would recoup that $200 in 3 months.

[Thymeclock]

Originally Posted by Angmaar

He would because the mod are free.

I think your answer deserves a prize, because it accurately addressed the salient point of the way in which the riddle was framed. The implication was one of who would save the most money after seeking (and presumably acting upon) the professional advice given. One proposal involved spending money (on a technical gizmo), the other in spending nothing. If neither took any action at all, the status quo would remain the same.

He saves by not spending anything, nor losing anything. His potential return is risk-free and his attaining anything more than zero is a pure benefit. She hopes to increase her benefit, but only after pinning her hopes upon and recouping the capital outlay spent on the (presumably not cheap) recommended whiz-bang, canoodle valve.

It's a case of 'money remaining in your pocket' while losing nothing yet possibly earning potential rewards vs. incurring a debt with hopes of attaining 'pie in the sky'.

[Christ]

My truck has already made up the difference in fuel costs between it and my previous vehicle, a consistent 28-29 MPG Dodge Caravan.

Sure, I used the Caravan to haul things as well (check out my albums), but the truck can haul SO MUCH more. Like half a cord of wood. TWO lawn tractors (and a trailer with 5 more on it). I can haul motorcycles without having to lower/remove the handlebars or other parts... and so on.

I went from 28-29MPG down to something like 17 (hard to keep accurate track because I'm going tank to tank... I only drive it when I need to.)

Oh, and my insurance went down $20 a month, as well. Guess that makes up for the fuel costs, a little.

I do have a Diesel Golf, that as soon as I get it on the road, will get a trailer hitch put on it, and stiffer suspension. Why? Cuz I'd be willing to bet that Diesel Golf can handle a 1,000 lb tow load just like my truck can... except it can get 40+ MPG of nearly free fuel doing it. I only with it was a turbo...

[texanidiot25]

Antique truck with 10mpg and high fuel mileage car? Why don't you just put my name in the riddle? (See sig)

[bgd73]

this is simple.

the conobox drifts to the wind and 22 guage tinfoil aero mods...
in todays dollars the 16guage fendered truck is 20 econoboxes...

he could haul the econobox.

if an antique vehicles value increases by just 1000 a year, it is another gain on the crap box risking life and limb with tiny wheels and tires....

the truck is not only saving money, it is gaining.

for every 1000 pound payload, it has to be proportianetly applied to the fuel mileage.

To drift off the subject.. I did not want to give my sube up for ayhting (I got the little 1781cc wagon).. I spotted two fairmont wagons with the 302 v8 installed, 5 speed, and welded...
for 10-20mpg less, I could have a car I could go fast in..and still be a wagon that can haul a bit more (not hat I have any complaints, the little sube is the biggest little car ever).. but you may get my point. Thinking larger may have larger bills, but it may return alot more than expected...no short timer eocnomy about it.
If one thinks their little hypermiler is normal... the disease is winning, like a bad cult.
no riddles about it. What exactly is getting saved? some drops in the bucket, and a scarier ride.