JohnnyRockets

You probably got something skewed, maybe up hill down hill. I used to experiment on a Tahoe you get way less on highway and slightly less for stop/go. It was DC traffic and hwy trip to NYC and PHL.

NCLSEA123

I've picked up E85 compatible cars where the gas mileage was somewhat less than expected on the first tank but improved when I filled up again with regular. I suspect in at least some of these cases, the person who returned the car had filled up with E85. I usually don't fill up with E85, unless it's at least 30 cents per gallon cheaper. I also would prefer not to slightly screw over the next person who rents the car on gas mileage.

kb9522

I always just use whatever octane is on the filler cap (not E85). I get more AA miles that way.

If I were the one paying for the fuel though, it might be a different story.

Wiley

I always try to find a E85 station before returning a car, but those gas stations are so rare that I've never been able to!

elCheapoDeluxe

That is a real a-hole move. If diesel is cheaper and you're only a quarter mile from the rental car facility, do you fill it up with that?

canyoncar

not saying that he should do what he's doing, but the only difference between flex-fuel and "regular" gas cars is the connections and the computer programming. E85 eats rubber so flex-fuel vehicles have no rubber lines/gaskets/etc at all, and there are sensors to detect when E85 is in the system so that the air/fuel ratio is adjusted accordingly.

I have a friend with an older (1970s) vehicle, he installed special teflon fuel lines so that he can run E85 in the truck for performance purposes (E85 has a much higher octane level than 87 gas.)

You can put E85 in a "regular" gas car and it will still run.. Diesel in a gas car, as you know, will kill the engine (or just make it run very poorly). Besides, you would have to go out of your way to put diesel in a gas car. Diesel pump nozzles are too big to fit in a gas car's filler neck.

Closingracer

Yes but you're also punishing the next driver. How would you like it if you say rented a Chevy impala and I had it before and filled it from empty with E85?


If a car can take E85 I will use it once in a while during a Rental but I will always fill it up with the minimum octane gas required before I return it . If it requires 87 than 87. If it requires 89 or 91 ( 93 since 91 is very rare in nyc at least where I fill up normally) than 89 or 93

canyoncar

notice the first line in my post "not saying that he should do what he's doing". The poster I quoted acted like the car was going to break down by putting ethanol in a regular gas car.

The only rental cars that I will put E85 in, personally, are flex-fuel vehicles.

dwbf11

Sure, and then you'd be on the hook for a $2K+ fuel system replacement!

This is terrible information. You should never put E85 in a vehicle not set up for it, even if the vehicle will run (albeit poorly, if at all). Your friend also probably has a standalone or custom ECU setup to account for the ethanol; it goes beyond a few extra sensors as you state. It's not just the damage to rubber parts that will take place over time, but the extra corrosive agents in E85 will damage any exposed soft metal in the fuel system such as aluminum.

canyoncar

Vehicles from the 1970s do not have ECUs.

jackal

I long ago learned to work under the assumption that the previous renter almost certainly did the same to me, so I'm just equalizing out being shorted and passing on what I got.

dwbf11

Perhaps his doesn't, but many did. My Volvo 242 does, for example (Bosch K-Jetronic). Many of the late 70's Cadillac models had it too. Either way, last I checked there were no classics out on the Executive Selection so this isn't really a productive argument. The original point is that you should not put ethanol in a non-E85 modern vehicle.

elCheapoDeluxe

My point being, you wouldn't ruin the fuel system if you knew you were likely to get caught. Is it really morally ok to ruin the fuel system just because someone else is going to get stuck with the breakdown long after you're gone? Maybe a future renter, maybe a future owner of the vehicle? I would say no. It is amazing the shabby things people will do to each other when they think "they'll never know it was me and I'll save $2.70."

JohnnyRockets

Correct, for E85 you will need an ECU for that otherwise the fuel mix will be wrong and car will run poorly but should still run. I would guess it might not run at all if you put E85 in a V12 Ferrari.
The only big issue is the corrosion of parts.

Check engine light will likely come on very soon so you WILL get caught. Otherwise, a rule of thumb, don't buy pre-owned rentals EVER. Any maintenance issue won't arise until they retire them from the lot.

I would say many people will do it if they can find one close enough. On a flex-fuel car of course. That is why I don't normally pick a flex-fuel car at airports that I know there is E85 nearby.

s0ssos

I think physically it is quite difficult to do that