1. Which ethanol are you talking about? There are many ways to make ethanol, some more efficient than others, and with different environmental impacts. Many studies seem to indicate that corn-based ethanol, which currently is most popular in the U.S., is not a very efficient way to produce ethanol. But there are many other feedstocks--sugar cane, potatoes, and other grains are also common in some places. Even sawdust.

Read about some estimates of the true cost of corn-based ethanol.

2. If you are only asking about the cost of fuel per mile, then consider that ethanol contains about 33% less energy by volume, compared to gasoline. This means that to break even, financially, in terms of cost-per-mile, you must pay 33% less for ethanol versus gasoline. For E10 (10% ethanol, 90% gasoline), that means you would need to pay 3.3% less (than for 100% gasoline)

3. Different fuels require different hardware. To run E85, for instance, you need a flex-fuel vehicle, which may have different manufacturing costs than a "standard" gasoline-only vehicle.

4. Ethanol also has a different octane rating than gasoline, which can affect engine performance (positively or negatively, depending on your engine specifications). Over long periods of time, this may either positively or negatively impact the cost associated with maintenance on your engine.

5. Different fuels may have difference maintenance-related costs associated with them, such as the types of fuel filters, pumps, injectors, timings, etc, that must be used (some of this is covered by the "flex-fuel" system, of course, which I already mentioned). And different fuel types may lead to failures--and thus replacement costs--of some of these systems more rapidly than others.

1. Which ethanol are you talking about? There are many ways to make ethanol, some more efficient than others, and with different environmental impacts. Many studies seem to indicate that corn-based ethanol, which currently is most popular in the U.S., is not a very efficient way to produce ethanol. But there are many other feedstocks--sugar cane, potatoes, and other grains are also common in some places. Even sawdust.

   Read about some estimates of the true cost of corn-based ethanol.

2. If you are only asking about the cost of fuel per mile, then consider that ethanol contains about 33% less energy by volume, compared to gasoline. This means that to break even, financially, in terms of cost-per-mile, you must pay 33% less for ethanol versus gasoline. For E10 (10% ethanol, 90% gasoline), that means you would need to pay 3.3% less (than for 100% gasoline)

3. Different fuels require different hardware. To run E85, for instance, you need a flex-fuel vehicle, which may have different manufacturing costs than a "standard" gasoline-only vehicle.

4. Ethanol also has a different octane rating than gasoline, which can affect engine performance (positively or negatively, depending on your engine specifications). Over long periods of time, this may either positively or negatively impact the cost associated with maintenance on your engine.

5. Different fuels may have difference maintenance-related costs associated with them, such as the types of fuel filters, pumps, injectors, timings, etc, that must be used (some of this is covered by the "flex-fuel" system, of course, which I already mentioned). And different fuel types may lead to failures--and thus replacement costs--of some of these systems more rapidly than others.