Is it worth reducing the cars weight by 45 pounds... by...

The difference in fuel economy will be imperceptible. But I'm not sure if there are problems with stale petrol in the tank, and if there are, you'd be preventing that problem by filling less gas more often.

 

Or do two runs on the same day, as close as possible, same gas, and just load up the hatch with sand bags or whatever.

 

I've had my PRIME for less than a month now, but so far I have filled the tank twice already. I am not too worried about the gas going stale during summer months for we frequently make long trips during summer. During winter, we don't do as much driving, so changing to winter mix gas before cold weather settles seems to be good thing to do. Ethanol free gas is very hard to come by in our area, so I am not going to look for that. My question to you all is, what octane rating gas are you using on PRIME? Is there any benefit in using higher octane gas than cheapest 87? I tested on Gen3 Pri, but there was no noticeable mpg difference when I used higher rating 94 gas, so I went back to 87.

 

As long as the weight matches the same amount of gas.

I just can't believe it's going to make a big difference unless we're talking about 100,000 miles of use. For me, much ado about not much.

 

Up here going to the highest octane is the one way I know, to get ethanol free. I've been reading that beyond metro Vancouver there might be a lot more, in all the grades.

 

87

Use the octane that your engine is built for. Octane is a rating of how fast your fuel burns and needs to match the engine. If you have a short srtoke piston engine, you need a faster burning fuel (lower octane). If you have a long stroke engine, you need a slower burning fuel that burns for the full stroke of the piston (high octane).

So the Prius is rated for 87 octane. If you waste $ and put in 92 octane, your gasoline is still trying to burn as it's going out the exhaust port. READ wasted fuel and money.

Some engines say it's OK to burn 87 but under load will perform better with 89-90. Those are actually long stoke engines that are under performing running lower than recommended octane even though the manual says so. My 2003 V8 Runner was like that. It ran OK on 87 but better on 92.

There's decades of misinformation and folk lore on this. Use what your manual says. 87

 

Thanks. That explains no mpg gain using 94 on Gen3. I will stick with 87 the cheapest on my PRIME.

 

We got about 10% better mpg, on one tank, a half-tank fillup of regular octane, from a small town Chevron, up the coast. This has me wondering about ethanol.

 

Let me complicate this more. Ethanol E10, E85 vs no Ethanol E0 fuel. We have a LOT of no Ethanol gas here. I can tell you from lots of testing that No Ethanol burns with more BTU's, IE more energy that Ethanol fuel. This means better gas mileage at the same octane (87) per gallon. The math problem comes in with the difference in price for each. The vehicle in question needs to gain enough increase in mpg to offset the higher price paid.

My testing with an 2010 Prius, 2003 V8 4Runner, 2014 V6 4Runner, and a 2014 Camry Hybrid shows the Prius has the best capability to take advantage of the no ethanol fuel's higher purchase price per gallon to offset about a $0.25 difference in in the two. All 4 vehicles got better mpg on E0, but only the Prius could maximise that enough to make it worth paying the higher E0 price.

Note this higher mpg effect for E0 is less on the less efficient winter blend of fuel (October through March here)

Confused?

I burn 87 octane E0 in both hybrids and E10 in the 4Runner.

PS, you can test this yourself. Just make sure if you start testing with E10, do the test, then get the tank near empty and run at least two tanks of E0 through it before testing for E0. Your ECU's need time to adjust and you want all the E10 gone for accurate results.

 

I have not seen any gas station that sells anything other than E10 around here. When I was looking for ethanol free gas for my small engine equipments, I had to go out of the way to find a marine fuel station for boats that sells no-ethanol gas, but the price was about x1.5 of the regular gas. I think 87 E10 is going to be in my PRIME, unless I find cheaper and more convenient source for E0 gas.

 

Are you saying you got 10% better mileage with no-ethanol fuel?

 

Yes. Which is nuts, isn't it.

We're normally around 4.4~4.5 litres per 100 km displayed, this time of year. That tank, a half tank fillup btw, displayed was around 4.0~4.1, without really trying hard.

 

A gallon of gasoline weighs 6.3 pounds, so you are talking about 70 pounds, not 45.

 

@Mark57 thinks E0 benefit mpg, so maybe. But again, even with 10% gain, I would not pay x1.5 of price for E0 around here.

 

It varies by state, but you cannot find automotive gasoline in California that does not have ethanol. I know that there are other sources such as marine gasoline, but I am talking about what you can find at an automobile service station. This may be seasonal, but you get whatever is in season. You can pick octane, but not ethanol.

 

I would like to reduce it by 45 lbs but I would have to buy all new clothes.

 

Today in OKC . . .
E10 = $1.90 / gallon
E0 = $2.23 / gallon

It's usually about $0.25 higher for E0 here. E0 rises in price faster and takes longer to come back down.

Buying it at specialty areas at marinas or for lawn equipment is like buying gas in a resort town. $$$$$$$ I understand many of you have little or no choice or availability.

In Oklahoma, I just point my pellet rifle at the ground and refine a new tank full when I get low.

 

Well, higher octane can have a longer shelf life. The octane rating drops as volatile fractions evaporate off. But that is more of an issue is less airtight tanks.

 

Ethanol percents aside, would higher octane lower mpg? It resists ignition better?