Gas/E85 difference: The fuel economy of our Tahoe on E85, under these conditions, was 26.5 percent worse than it was when running on gas.
A motorist, filling up and comparing the prices of regular gas and E85, might see the price advantage of E85 (in our case 33 cents or 9.7 percent less) as a bargain. However, since fuel economy is significantly reduced, the net effect is that a person choosing to run their flex-fuel vehicle on E85 on a trip like ours will spend 22.8 percent
more to drive the same distance. For us, the E85 trip was about $30 more expensive — about 22.9 cents per mile on E85 versus 18.7 cents per mile with gasoline.
The Final Score Card — Performance
We were also interested to see if there was a clear difference in performance. Here, the news was better for the renewable fuel. While the test times were generally slower for E85, the difference was small enough to go unnoticed by most drivers. Despite E85's higher octane rating (103 here) the flex-fuel nature of the Tahoe's 5.3-liter V8 engine prevents it from taking full advantage.
Final results
| 0-60
| 1/4 mile
| 50-70 passing, uphill (sec.)
| | |
|---|
| time (sec.)
| time @ (sec.)
| speed (mph)
| Cajon Pass
| Baker Grade
|
Gas
| 9.3
| 16.7
| 84.2
| 7.6*
| 7.2
|
E85
| 9.8
| 17.0
| 82.7
| 7.2
| 7.3
|
* delayed kickdown
Environmental Comparison
E85 is often heralded as a way to reduce air pollution. Since increasing concern about global warming has focused attention on greenhouse gases, we decided to track our carbon emissions during this test.
By relating our observed fuel economy to CO[SUB]
2[/SUB] emission figures found in the EPA's
Green Vehicle Guide we determined that our gasoline round trip produced 706.5 pounds of carbon dioxide. On E85, the CO[SUB]
2[/SUB] emissions came to 703.1 pounds. The difference came out in E85's favor, but only by a scant 0.5 percent. Call it a tie. This is certainly not the reduction in greenhouse gas emissions we had been led to expect.
) and are thinking about pulling our trailer back there next summer for a long overdue visit.
