I've recently had the chance to buy some 'real gas' on a few fill-ups, Canadian gas without ethanol. The graphic shows that I'm getting about 50 mpg on regular E10, but about 58 mpg on the no-ethanol gas. Since E0 has only about 4% less energy than regular E10, getting 15% better mileage doesn't make sense purely from thermodynamics. Does anyone know if the Prius computer might be programmed for E0, and therefore possibly doesn't do as well on E10? And if so, can we re-program the computer?
1) ethanol has only 66% of the energy as gasoline, so E10 should get 3% less mileage, in theory. Ethanol fuel - Wikipedia, the free encyclopedia 2) In practice, the Prius seems tuned for summer blend E0 gas. It appears to many owners as if the Prius treats ethanol and butane as 'filler', not fuel. (Most cars get better mileage on winter gas than summer) http://en.wikipedia.org/wiki/Gasoline#Volatility
Huh? I've always understood the opposite. The lower vapor pressure of summer gas is associated with higher density, thus higher energy content than winter fuel. And this is also responsible for a portion of the higher summer price. Or is this something that has changed in recent years as blending requirements changed?
Canadian gas without ethanol WHERE WAS THAT? I thought most provinces and about 10% in reg gas Did you get your conversion factor right ?
Summer-grade gas cuts pollutants, raises prices - chicagotribune.com They add oxygenates, which improve complete burning, but oxygen is not fuel.
Part of the reason fuel prices are so high in certain areas (Chicago is a good example) is due to boutique fuel blends. If Chicago's supply runs low, we can't just "go next door and borrow a cup", because next door's fuel blend doesn't meet our requirements. The way I see it (and please correct my logic if I'm mistaken), is there should be four blends (summer low altitude, summer high altitude, winter low altitude & winter high altitude). These four specs should be mixed to meet the most stringent requirements of any locale falling into each category. For example, if SoCal's fuel requirements are the most stringent for the low altitude blends, then that formulation would apply to all low altitude areas. I would reason that doing this would provide some flexibility in the supply chain as well as realize greater economies of scale.
A local NH gas station gets their no-ethanol gas from Canada. Don't know how. But the car sure likes it, as the gas mileage shows in my OP. Re: the conversion factor, I thought it was 4% less energy in E10, but I was corrected. It is 3%, which makes my 15% increase in gas mileage even more puzzling. I am wondering if the Prius programming could/should be optimized to E10, since my experience, albeit limited here, suggests that E10 mileage is so much worse than it should be.
I wouldn't believe the MID numbers for a second. They sure look nice but reality will set in at the pump. My MID is ~7% optimistic. A closer approximation is achieved by adding the miles on the tank to the miles to go then divide by 10. If your results are calculated wait until you have the results from the next (current) tank. If it is average then the 2nd was a good tank. If it is low then you had a fueling problem & 2 average tanks. I'm still trying to get my 1st 60. Good luck.
You are absolutely right on raising the cost. There is a lack of refinery capacity and every time they have a different product they need to change over. Differing requirements change the efficiency of the fuel, so oil companies do not want to send a stricter blend that would give drivers fewer mpg. The best solution is for the regions to get together and figure out a formulation. That way if there is a performance hit on the blend all the gasoline will have a similar fuel economy. The ethanol requirement is another problem. Its enforced by law twice as a subsidy so that ethanol can compete with gasoline, and as a mandate. This doesn't make any sense at all. Without the subsidy gasoline prices would rise about 6%. Without the mandate to use corn ethanol, and allow other bio fuels even this would go away and perhaps a gasoline tax would allow us to decide at the pump whether we want e10 or not.
I thought he pick the gas in Canada so it would be Litres to US gallons Also Irving sell a lot of fuel to the US Irving Oil | Our Refinery
E10 has about 3.33% less energy per gallon than conventional fuel. Conventional fuel has about 3.45% more energy per gallon than E10. Math is funny that way. Going from E10 to conventional fuel should increase mileage by 3.45%. The O2 sensors will sense stoichiometric mixture and adjust the injectors' duration accordingly. The car isn't "tuned" for either fuel. The ECU has to be able to adjust for up to E10, but I wouldn't say it's "tuned" for it. As for the display, there are two ways to estimate fuel flow: 1. correlate injector timing with fuel-quantity-injected, then add up all the little quantities. 2. Measure airflow (at the MAF) and assume stoichiometric fuel for that airflow...estimate fuel flow accordingly (with an assumed 02 demand per gram and density) and integrate. Method 1 would capture the effect of E10 requiring more volume, and method 2 would not. I don't know how the Prius MID/ECU's work. I can say that on the Oklahoma (non-E10) gas I buy, the MID is dead-nut accurate as measured by miles / pump-volume.
Non-Ethanol gasoline is the only thing I buy when I have a choice. My own personal testing on multiple vehicles over several years including the Prius bears out I get better MPG with Non-Ethanol gasoline. Fortunately in OKC we've been able to dodge the bullet and stay with a conventional Non-Ethanol blend during the summer. Lots of wind is not always a bad thing.
Here in Oregon we have no choice. Ethanol 10% in gasoline is required by Oregon for all gasoline motor fuel ALL YEAR LONG. I did notice that in Arizona back in March 2010 when I used reg gas and no ethanol blend it was easy to get 60 MPG on the hwy at 60-65 MPH. With Ethanol 10% blend at the same speed and all things being equal my MPG is 55-58 MPG. Ethanol in my opinion is not a fuel extender and more fuel is used to make Ethanol than its worth. Its like paying $1.00 for 65 cents. Alfon
Right, so why am I getting 15% better mpg (calculated, not MID) on non-ethanol gas, tank after tank? See OP for graph of mpgs per tank. This suggests to me that the programming for the Prius is not optmized for the E10 that most of us use. A software adjustment could improve how the car drives. One example: on E10, if I just barely touch the gas pedal on a level road at 30mph, the mpg drops to 20 on the MID. But using E0, same conditions, the MID stays at 40 mpg.
