Wednesday, July 9, 2008

The great gas MPG challange!!!

So the other day on the radio they were talking about how John Warner has proposed setting a national speed limit of 55 mph to lower gas use in the US. Well, one of the callers happened to mention something about the affect of ethanol on gas mileage and it started me thinking.....

I'd already noticed with new vehicles running on E85 that the listed gas mileage was much less than ordinary fuel. For instance, a Chevy Tahoe Vortec 5.3L V8 gets 14/20 mpg with normal fuel, but only 11/15 mpg with E85.

But how about a 10% blend that is very common at filling stations in my part of the country?

I've used the 10% blend all of my driving life (has it really been 23 years?) because it was usually cheaper and I thought "gas was gas". But with prices now at $4.00 per gallon, a small difference in mileage can make a difference.

So here are my rough calculations. My truck (99 Ford Range, manual transmission) gets just under 24 mpg.
  • For 10 gallons of 10% ethanol blend gas at $3.90 per gallon, it costs me $39.00.
  • For 10 gallons of non-ethanol blend gas at $4.00 per gallon, it will cost me $40.00, or $1.00 more than with ethanol.
  • $0.10 difference between the two gas types seems about right from looking during my drive in today.
With the 10% ethanol blend gas I can go just under 240 miles on 10 gallons.
If I get a 1 mpg increase in gas mileage with the other gas, it means 250 miles per 10 gallons, or 10 additional miles.

10 additional miles would take 0.42 gallons of gas (at 24 mpg). 0.42 gallons of gas at $3.90 per gallon = $1.63.

So..... if I see a 1 mpg gallon increase in gas mileage from use non-ethanol gas that is $0.10 per gallon more expensive..... I will save $0.63 per 10 gallons of gas.

A 2 mpg increase would save me $1.26, 3 mpg = $1.89, etc.

Is this a big deal? Not really I guess. But it would illustrate just how buying the less expensive item is not always cheaper. If gas were $2.00 per gallon and there is a 1 mpg difference it would be cheaper to get the ethanol blend. This is very counter intuitive. I've heard of many people switching and using ethanol blend to save money, but in the long run they may be paying more.

But wait...... I haven't done the test yet. Maybe ethanol doesn't really impact my gas mileage. Maybe it improves it? It takes me a week to drain my tank with normal driving to work so expect another post with results in a little over a week.

This should be interesting!

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