E85 vs. Gasoline - Economy & Consumption
Reality Check: Which is cheaper to drive with, eFlexFuel + E85 or Gasoline?
E85 may be cheaper than gasoline but due to its chemical composition, it also gets lower MPG compared to gasoline. So which fuel is actually more economical to run?
It’s been drilled into our heads to think of MPG when we consider fueling costs, but this logic goes out the window when different fuels cost different amounts. To determine which fuel is actually cheaper, we need to think about fuel efficiency and fuel costs together, which can be expressed as range per dollar.
Range Per Dollar: The True Measure of Fuel Efficiency
While miles per gallon (MPG) dominates fuel discussions, cost per mile and range per dollar better reflect real-world savings when comparing fuels of different costs. Below is a direct comparison of range achieved with $30 using example U.S. fuel prices for eFlexFuel E85 Vs. Gasoline:
| Fuel Type | Price/Gallon | Gallons per $30 | MPG | Range | Cost per Mile |
|---|---|---|---|---|---|
| Gasoline | $5.00 | 6.0 | 25 | 150 | $0.20 |
| E85 | $3.25 | 9.2 | 20–22.5 | 184–207 | $0.14–$0.16 |
Key Takeaways:
- Spending $30 on gas gave a range of 150mi while spending $30 on E85 gave a range of 184–207 miles. That’s 23–38% more range per dollar with eFlexFuel & E85 Vs. gasoline.
- It cost 20 cents per mile to drive on gasoline but only 14–16 cents per mile to drive on E85. That’s a 20–30% decrease in fueling costs.
- It would cost $4,000 to drive 20,000 miles on gasoline. It would only cost $2,800–3,200 to drive the same distance on E85. That’s a savings of $800–$1,200 savings by driving with eFlexFuel + E85 Vs. Gasoline.
Curious about the math used to achieve the summary above? We’re happy to spell it out.
+Assumptions
- Assume the vehicle averages 25MPG on gas
- Gas Price: $5.00/gallon
- E85 Price: $3.25/gallon
In some cases the price gap between E85 and gas is even bigger, making savings even greater!
+Analyzing gasoline fueling costs
- If gas is $5.00 per gallon and you are spending $30, you’ll get 6 gallons of gas. ($30/$5 per gallon = 6 gallons)
- If your vehicle gets 25MPG on gas, you’ll have a total range of 150 miles. (25MPG x 6 gallons = 150 miles)
- That means $30 of gas got you 150 miles, which is the same as paying 20 cents per mile in fuel costs. ($30 / 150 miles = $0.20 per mile)
+Analyzing E85 fueling costs
- If E85 is $3.25 per gallon and you are spending $30, you’ll get 9.2 gallons of E85. ($30/$3.25 per gallon = 9.2 gallons)
- If your vehicle gets 25MPG on gas, we can estimate you will get around 20-22.5MPG on E85. (10-20% decrease of MPG)
- If you get 20-22.5MPG on E85, you’ll have a total range of 172-193.5 miles. (20MPG x 9.2 gallons = 184 miles & 22.5MPG x 9.2 gallons = 207 miles).
- That means $30 of E85 got you 184-207, miles which is the same as paying 14-16 cents per mile in fuel costs. ($30 / 184 = $0.16 & $30 / 207 = $0.14)
The Science Behind eFlexFuel + E85’s Fuel Economy
Energy Density and Combustion Efficiency
E85 contains ~75% of gasoline’s energy per gallon (83,950–95,450 BTUs vs. 114,000–120,000 BTUs). This difference explains the MPG reduction but doesn’t translate to a direct 1:1 loss due to:
- Higher octane (100+) enabling advanced ignition timing and cleaner combustion.
- Ethanol’s cooling effect, which increases air density in cylinders for better efficiency.
- eFlexFuel Optimization mitigates MPG losses through:
- Real-time ethanol sensing: Measures ethanol percentage 100+ times/sec for precise air-fuel ratios.
- Fuel system cleaning: Ethanol’s solvent properties reduce carbon deposits, improving efficiency over time.
- Flexible blending: Drivers can also use E30–E50 or mix gasoline for a balance of efficiency and performance.
How much can you save? Use the Cost Savings Calculator Below:
Average annual mileage is around 15,000 miles.
Most cars average 30mpg, most SUVs average 25mpg, and most trucks average 18mpg.
Running E85 requires more fuel. Smaller vehicles (e.g. Toyota Prius) may see a decrease around 10-15% while larger vehicles typically see a decrease of 15-20% MPG.
If you don't know how much E85 costs in your area, visit E85Prices.com
Consider whether your vehicle requires Standard or Premium gasoline.
If you don't know how much gas costs in your area, visit AAA's gas price map.
About Fuel Consumption help
Consumption on E85 varies depending on what kind vehicle you drive. Usually smaller and newer cars have lower consumption increase compared to gasoline than bigger and older cars. Hybrids also tend to have smaller consumption increase. This is due to the fact that newer vehicles tend to be more able to benefit from E85's better knock resistance than older vehicles. In emission lab conditions, by measuring fuel weights, we have generated as low as 12% difference between regular gasoline and E85 on a hybrid vehicle.
Driving style/environment also affects how much E85 mileage turns out to be compared to gasoline. Fast driving with varying speeds and a lot of accelerations tends to lower E85 mileage (20 to 30% lower than of gasoline) while easy driving with steady speeds for long sequences tends to generate significantly higher mileage (10 to 20% lower than gasoline). With E85, this phenomenon is amplified compared to gasoline. More performance oriented engines typically run with slightly rich AFR for safety reasons and this increases the consumption in demanding driving conditions and in high output engines.
saved
in 3 years
metric tons CO2 saved in 3 years
Equally to plant and grow trees annually
Flights from L.A. to San Francisco
