>> I use regular but I do spend a good portion of my commute going up.
>> Mid grade would give me more juice up hill?
>
> Yes, because the knock sensor won't be telling the ignition to
>retard the timing as much. Under those conditions you'd probably get
>better mpg with mid grade.
>>>I use regular but I do spend a good portion of my commute going up.
>>>Mid grade would give me more juice up hill?
[quoted text clipped - 5 lines]
> Thanks for the Advice, now using the midgrade and I get 1 1/2 more
> trips to work on my one tank
You're welcome. As a general rule you get better MPG with regular if
the engine isn't being strained. If it is, you get better MPG with a
higher octane gas.
>> Yes, because the knock sensor won't be telling the ignition to
>>retard the timing as much. Under those conditions you'd probably get
>>better mpg with mid grade.
>
> Thanks for the Advice, now using the midgrade and I get 1 1/2 more
> trips to work on my one tank
It must be a short trip to work. I don't think I've ever seen a claim
of more than 5% for the improvement of using premium (much less plus)
in a car that can take advantage of higher octane fuel (not all cars
can). Of course if your car was designed to run on premium and you are
trying to use regular, the decrease on regular can be much higher than
5%. The only reason I can think of to use plus, is if you car spark
knocks on regular and you need that slight (and I mean slight)
increase in anti-knock performance offered by the plus grade.
I have a Nissan Frontier V-6. According the owners manual, Regular
Fuel is recommended, but Premium will provide superior power and fuel
economy. So I ran a test. I keep detailed gas mileage records and
drive the same sort of pattern consistently. I ran regular for many
miles until the engine was broken in, then ran premium for about 2000
miles, then regular for a bout 4000 miles, then premium again for 3000
miles, then back to regular. My conclusion was that premium did
actually provide better fuel economy in that engine - around 3%. That
was not enough to justify the higher cost of premium. However, it was
obvious that the engine management system was able to take advantage
of the higher octane by adjusting engine parameters (ignition timing,
cam timing, etc.). I have run this experiment on several other
vehicles that claim to be able to take advantage of premium and not
gotten the positive results I saw with the Frontier. Since I got good
results running premium instead of regular, I tried the plus grade. It
did nothing. I got no increase in fuel economy at all. My conclusion
was that Plus is a rip off unless you need a minor increase in octane
to avoid spark knock. Around here regular has an AKI of 87, plus - 89,
and premium - 93. If you really want an AKI of 89, wouldn't you be
better off buying 10 gallons of regular and 5 gallons of premium?
Ed
mjc13<REMOVETHIS> - 10 Dec 2007 15:31 GMT
>>> Yes, because the knock sensor won't be telling the ignition to
>>>retard the timing as much. Under those conditions you'd probably get
[quoted text clipped - 34 lines]
>
> Ed
Wrere any of the "other vehicles" cars like the Camry four, where
you havr a very efficient but large four cylinder engine driving a
mid-sized sedan with a high-efficiency automatic transmission? This car
is more capable than most of taking advantage of optimum conditions.
It's the only car its size that I know of that can average 34mpg in
mixed driving. This number can be dramatically lower if conditions
aren't optimal, though: step too hard on the gas when accelerating, use
the wrong grade of fuel for the terrain, have a plugged air filter, and
you can easily lose 4 or 5 mpg...