Higher octane for better mileage?

[Airstreamer67]

I just filled my tank with Shell regular at $1.96 per gallon. Premium was an unbelievable $2.50 per. It usually isn't at that large of a disparity level, but it was this morning.

I only run RUG with 10% ethanol in my '15 Mazda 2.0L automatic. I've thought about using non-ethanol and/or premium, but the price differential is just too large to justify it. At a 42.6 miles-per-gallon running average, I'm getting better mileage than the EPA estimate, so I'm happy. I think I'm getting about as much as I can with the least-expensive fuel available, so I see no advantage in changing what I'm doing now.

Fuelly says my lifetime fuel cost per mile with this car is at 4.5 cents after 18,000 miles, so that's good enough for me.

[14Corolla]

Just received my fuel credit card bill. Is so nice to have only one fill up on it.
Tank I'm on is going over three weeks. Could easily make four.
I is one happy camper.

[Draigflag]

I'm not sure whats going on with the diesel I put in mine last fill up, but it feels higher octane than usual, there's a noticeably louder noise from the engine and it feels more responsive, picks up speed quicker with less input. It's also indicating 68.2 MPG so far, with 450 miles travelled, I've got just over half a tank left.

Must be a good batch, I used the same station I always use.

[BlueRover]

Originally Posted by Draigflag

I'm not sure whats going on with the diesel I put in mine last fill up, but it feels higher octane than usual,

I always thought that octane is only used in gas/petrol while "Cetane number" is the standard for Diesel fuel. Is it different in the U.K.??

[BlueRover]

Originally Posted by Airstreamer67

I just filled my tank with Shell regular at $1.96 per gallon. Premium was an unbelievable $2.50 per. It usually isn't at that large of a disparity level, but it was this morning.

Don't worry be Happy LOL

Last fill up was at $1.449 a litre X 3.78 (app) = $5.48 for a U.S. gallon Cdn or $7.30 when converted to U.S. Dollar. 94 octane non ethanol

Regular fuel was $1.29 or $6.50 per U.S. gallon in U.S. funds 87 octane up to 10% ethanol

Oh it was at a Chevron

[Draigflag]

Originally Posted by BlueRover

I always thought that octane is only used in gas/petrol while "Cetane number" is the standard for Diesel fuel. Is it different in the U.K.??

Yea you could be right, I'm no expert on fuel to be fair, but this tank feels like it has the same effect as it did on my previous petrol car on performance/economy when using higher octane fuel.

[benlovesgoddess]

The first time i used Shell V power was diesel in my i20 - and it delivered my worst ever, and only sub 50 mpg tank for that car! Kept me off the Shell forecourt for years. Thought i should test the petrol though, and got a decent 69.9 mpg for the Prius.
Due to having my first service, i was running late for a theme park (if i'm on a day out, i like to be there as it opens, not at midday!), so i booted it down the motorway at 70-80 mph. The drive was stressful, as very few people drive on the left unless overtaking, most sit in the middle and outside lanes at an unsafe distance behind each other.
Overtaking, you had to push in - middle lane hogs too lazy to even move to the empty outside lane to let you out. Over 100 miles and a pitiful 54 mpg (indicated). We managed to fit all the rides in though.
Driving back at 56 mph in the slow lane, adaptive cruise control on, was a treat. No hassle, nothing to overtake, listening to music and 88 mpg (indicated). Late home, but a much more pleasant experience.
At the dealers we sat in all the Toyotas and some of the Kias.
Only thing i was a bit jealous of was a full glass roof in a Yaris, would have loved that option. No other cabin really stood out as much as mine (must be all that unpopular white!) - and no heads up display in any of them.
Suprised by the Kia Optima plug in hybrid, a big handsome saloon. Nice green eco trim details. At £33,000 a bit more, but with 27 miles (claimed) electric range per charge, economical enough to recoup the extra?
They said could be charged from a standard socket - though bet my boss still wouldn't let me dangle a wire out the window...!
After a poor showing from my Hyundai, i am afraid i may be put off Kia too, despite their popularity.

[Draigflag]

There are a ton of plug ins hitting the market now, the Mitsubishi Outlander is the UK'S best selling plug in, may even outsell the Prius as a hybrid. But I feel plug ins are a bit flawed, the ev range is usually about 30% less than quoted, so a 30 mile range is usually about 18/19, and unless you charge the car at home, then at work twice a day, then the milage will be poor. On long journeys where you might only have 1 charge, you're just driving a big heavy petrol car, so expect poor MPG. I read a review of the Optima the other day, rated at 176 MPG, they managed 28 MPG...

[14Corolla]

Originally Posted by BlueRover

I always thought that octane is only used in gas/petrol while "Cetane number" is the standard for Diesel fuel. Is it different in the U.K.??

Automotive class taught me that if Diesel had an octane number. It would be very high. Just like Jet fuel would be very high octane also.

I can only rationalize that what was experienced with 'better' performance with a tank of diesel is that a small amount of gasoline got into the tank. I mean the tank of the diesel station. Try gasoline in a diesel? You'll blow the engine apart.

[Draigflag]

Diesel engines are stronger, Fifth gear tested the "wrong fuel" scenario a few years ago, the petrol car with diesel didn't drive very far, but the diesel car with petrol in it drove ok, and kept going and going, and then they drained it, refilled it with diesel and it still kept going. They were pretty old cars though, modern engines are far more sensitive.