Gas Mileage Drop

KI track the mileage on my vehicle every time I fill up. Since sometime last year when I found it impossible to buy pure gasoline, my mileage went from 22 MPG down to 19 on a consistent basis. All my maintenance is kept up as scheduled and I am not expeeriencing any other problems. Can 10 to 15% ethanol mixed in really kill 3 mpg on the average??

Ethanol gas will reduce your mileage and power slightly. Exact amount depend on what, where and how you drive.


Yes, ethanol alone can account for a drop of several mpg.

My cars both lose about 3 mpg on ethanol as compared to straight gasoline.

And the winter mix drops gs mileage, too.

Thanks for your response - I had heard that elsewhere from several sources and wanted to check it out amongst the well informed listeners of Car Talk.

Thanks! Hopefully we’ll be converting to spring/summer mix soon and I can gain about one MPG to at least make me feel better. I’m thinking about going down to the Gulf of Mexico and taking a big tank with me to skim up some of BP’s finest…

Good to know! We’re both experiencing about the same loss in mileage. I hope that someday the auto manufacturers will develop an engine that’s meant to run on more ethanol and get better mileage. i think what we’re seeing now with “flex fuel” vehicles is still not quite there but perhaps with more research and development and the continuing rise in the price of oil we’ll finally see an honest to gosh efficient ethanol/gas engine.

I hope that someday the auto manufacturers will develop an engine that’s meant to run on more ethanol and get better mileage.

That would break the laws of physics. Ethanol simply generates less heat when burned. Because ethanol contains oxygen it is effectively partially burned.

Pure ethanol has about half the energy of pure gasoline. Those E85 cars get really lousy mileage if they use E85. There’s no savings even if E85 were cheap.

Ethanol is a huge scam. Almost as big a scam as global warming.

It is well within the laws of physics to get better MPG with ethanol than we currently do. Ethanol has a higher octane rating than our usual gasoline so it can be used with a higher compression ratio and higher combustion pressure for greater efficiency than when run in an engine designed for gasoline. Problem is that higher pressure alters the combustion chemistry and produces more oxides of nitrogen.

Ethanol is a bad “solution”.

Ethanol doesn’t appear to be a huge scam in Brazil, where they make it out of sugar cane.

How exactly is global warming a scam? I agree some of the science is still questionable, but I would love to know how you have made up your mind that it is a scam.

Is Darwin’s Theory of Evolution a scam too? Do you think the world is flat? Was the moon landing a scam as well?

How do you get over your paranoia about Flouride in the drinking water? Did you do it by obsessing about the President’s birth certificate?

If ethanol were viable, why can’t it compete in a free market without billions of dollars in subsidies and government mandates to use it?

As for global warming, it would take pages and pages to describe the fallacies in the Algore version of global warming. Issue #1, looking way back at the correlations between carbon dioxide and temperature, what historically has happened first, a rise in CO2 or a rise in temp? Answer, rise in temp has preceded rise in CO2. Rise in CO2 has never lead to a rise in global temps. Solar output among other variables has much greater influence on temp, not CO2. Many examples in history of much higher global temps when CO2 was less concentrated & many examples of historical times when CO2 was in much higher concentrations but earth was cooler. Many good books and websites where you could educate yourself on this topic. Richard Lindzen and Fred Singer are especially knowledgeable and informative.

Why does our government go out of their way to prohibit the importation of ethanol from Brazil?

David Pimental, a leading Cornell University agricultural expert, has calculated that powering the average U.S. automobile for one year on ethanol (blended with gasoline) derived from corn would require 11 acres of farmland, the same space needed to grow a year’s supply of food for seven people. Adding up the energy costs of corn production and its conversion into ethanol, 131,000 BTUs are needed to make one gallon of ethanol. One gallon of ethanol has an energy value of only 77,000 BTUS. Thus, 70 percent more energy is required to produce ethanol than the energy that actually is in it. Every time you make one gallon of ethanol, there is a net energy loss of 54,000 BTUs.

Mr. Pimentel concluded that “abusing our precious croplands to grow corn for an energy-inefficient process that yields low-grade automobile fuels amounts to unsustainable subsidized food burning”.

Ethanol is more like 2/3rds the energy content of gasoline per unit volume.

It is a scam.

Why does our government go out of their way to prohibit the importation of ethanol from Brazil?

Answering a question with a question is not proof of a scandal. Do you have anything other than speculation? Do you have any actual proof?

Okay, so now you are changing your story? Now you rail against corn-based Ethanol, and you make a good case. Why is sugar cane Ethanol and switch grass Ethanol a scam? You weren’t so selective in your condemnation of Ethanol, only in your defense of your assertion that it is a scam.

I don’t see how energy inefficiency in current production makes Ethanol a scam. We just need to find better ways to make it using sustainable energy and in a more efficient manner. All I see is criticism of current production methods, which can stand some improvement as the technology improves.

Even though Ethanol is less energy dense, it still burns cleaner than gasoline.

I am aware Ethanol contains less energy per gallon than gasoline. I don’t see why that makes it a scam. Could you please explain your reasoning better?

Even though Ethanol is less energy dense, it still burns cleaner than gasoline.

I agree that the Al Gore presentation can stand some criticism. That isn’t what I am talking about. I am talking about the fact that Carbon Dioxide is now at alarmingly high levels, and we are seeing this affect fragile ecosystems everywhere.

What I don’t understand is, even if we disagree about global warming, why can’t we agree that clean air is good for our health? Isn’t clean air worth fighting for even if global warming weren’t man-made?

I’m for freedom. Freedom to burn ethanol if you want to, freedom to produce it, freedom to import it from Brazil. I’m not in favor of the federal government taking my tax dollars to subsidize huge corporate corn growers, Monsanto, and ethanol producers. I’m also not in favor of the government forcing me to use ethanol in my cars, motorcycle, snowmobile, and lawn mower. The alcohol in the ethanol ate away gaskets in my Goldwing carbs - forcing a major repair.

It’s a scam (not-viable) if it relies on government force for its survival.