S70 Running of E85 for 3 years
I have an 1998 S70 that I ran exclusively on E85 for 9 months here in Tucson, AZ with NOTHING being done to the car.
The gas mileage went from 25 miles/gal to 19 miles/gal on a mixed highway/street profile. That is more or less what is predicted with the decreased energy content of the fuel.
Sometimes, the car had issues starting up, but after two or three attempts, the engine would turn over. The issue got worse on colder days (40 F and lower)
No mechanical problems at all. The only empirical evidence that I have is that the car still runs. I have not noticed any leaching or problems with fuel supply or rubber materials. My Volvo just keeps on going.
Check Engine Light
At concentrations above 50% ethanol, the check engine light comes on. The error code has to do with fuel/air ratios. If I bring back the concentration to E15 or "normal gasoline," the check engine light disappears. The light appears once again if I bring up the ethanol concentration over 50%.
No leaks of any sort
Subjectively, the ride seems to be smoother, but that might just be my bias.
Since there is about a 25% decrease in fuel mileage, I needed the price differential to be around that. For a month or so, I broke even, but then the differential was not enough. Nevertheless, it it is rewarding that I can pay a little more and be off the oil grid. I made a spreadsheet documenting part of the experiment.
This is my experience and only my own. Experiment at your own assumption of risk. I have no ties with any oil or ethanol major and no axes to grind.
Hypothesize all you want about why ethanol can't be/shouldn't be used on cars, but at least I can say that I can run my S70 with E85.