[TestDrive]

Originally Posted by Formula413

Is there a way to display L/100KM or G/100M in the fuel logs here at Ecomodder?

I don't think so. Fortunately, the math is pretty simple.

100/MPG = GP100M

It's probably something of a chicken and egg thing. People are accustomed to MPG and its hard to persuade them to use something less familiar, so MPG is in the fuel logs. And people remain unfamiliar with GPM, GP100M and GP1000M ratios because they're never exposed to them. FWIW - MPG is a FE (economy) ratio and GP100M is a FC (Fuel Consumption) ratio.

For an example of how the GP100M make everyday, pocket book calculations much more obvious, consider the previously mentioned Car Talk "Puzzler".

Here it is as originally presented.

You drive a gas-guzzling SUV that gets a whopping 10 miles per gallon. Your sleek and efficient spouse drives a sleek and efficient hybrid that gets 100 miles per gallon.

Now, let's assume that both of you drive the same distance each year. Your spouse sees an ad for a new, super-duper hybrid that gets 200 miles per gallon. She is lobbying to trade in her old, wasteful 100-mile per gallon hybrid for the new 200-mpg model; her thinking being that getting this new hybrid to replace the old one will really improve the average miles per gallon of your household.

On the horns of a dilemma, you seek out the one person you trust with questions automotive: your mechanic, Crusty!

"What can I do," you ask, "to improve our household's miles per gallon without buying this new hybrid?"

Crusty says, "Well, if we tune up your old SUV, and inflate the tires correctly, and remove that four inches of accumulated bird poop on the roof, I'm pretty sure we can get you all the way up to 11 miles per gallon." Your heart sinks.

What should you do? That's the question. Under which scenario would your household see the biggest improvement in miles per gallon: by getting the new hybrid, or by tuning up the old SUV?

Get out your calculator then check your answer - Read Click and Clack's answer


Here it is rewritten in terms of GP100M.

You drive a gas-guzzling SUV that gets a whopping 10 gallons per 100 miles. Your sleek and efficient spouse drives a sleek and efficient hybrid that gets 1 gallon per 100 miles.

Now, let's assume that both of you drive the same distance each year. Your spouse sees an ad for a new, super-duper hybrid that gets 0.5 gallons per 100 miles. She is lobbying to trade in her old, wasteful 1 gallon per 100 miles hybrid for the new 0.5 GP100M model; her thinking being that getting this new hybrid to replace the old one will really improve the average gallons per 100 miles of your household.

On the horns of a dilemma, you seek out the one person you trust with questions automotive: your mechanic, Crusty!

"What can I do," you ask, "to improve our household's average gallons per 100 miles without buying this new hybrid?"

Crusty says, "Well, if we tune up your old SUV, and inflate the tires correctly, and remove that four inches of accumulated bird poop on the roof, I'm pretty sure we can get you all the way down to 9 gallons per 100 miles."

What should you do? That's the question. Under which scenario would your household see the biggest improvement in miles per gallon: by getting the new hybrid, or by tuning up the old SUV?

Unless you're truly math challenged, this is not a puzzler. Reducing the SUV's GP100M fuel consumption by 1 is obviously better than a new Hybrid that only reduces GP100M fuel consumption by 0.5!

(Even more obvious, if you can, dump the SUV and you drive the 0.5 GP100M hybrid.)