MJImport

iTrader: (1)

Opinions and "facts" vary on this subject. There have been many publications both in support and in opposition.
I guess I probably would not use it on my Lexus but I have used it before on other vehicles and saw no difference to speak of.

bluelex

I edited your thread so it doesn't confuse people.... I have broken down the numbers personally just cause I like numbers and I used my gas prices here in WPB as an example..

Reg $3.84
Premium $4.09

$0.25 diff.

Rough breakdown: GS tank hold I think 16 gallons so that equals out to a $4.00 difference at every fill up. Roughly

GS3 last about 330 miles per tank on premium, less on reg. so I gather that lets say you need to fill up a total of 8 times a month which is twice a week. Again I just estimating here. I would only need to fill up 6-7 times when I daily'd her but I'm throwing high numbers here to make an example.. so 8 fill ups means that at the end of the month you have spent $32 more each month to put great gas in your. If you only fill up on average 6-7 times a month than your talking about $24-$28 a month but the deal breaker for me is that with Reg you lose gas mileage so lets say you actually lose 30 miles per tank by using Reg, might be a little more but again I'm estimating, what that actually means is that you will need more regular gas to match the prmium gas mpg. So that means your spending more on reg to match premium. So if your losing roughly 30 miles per tank that breaks down to 30x7 tanks. your losing about 210 miles a month. does that sound right to you guys? Lets just say you have to buy a 1/4 tank of gas more of reg a month to match what would avergae on premium. A 1/4 of reg is 4 gallons so 4 x $3.83 is $15.32 so now take that off the $32.00 you were paying extra it comes down to you save a total of $16.68 a month by using cheap gas VS Premium gas.

These numbers are rough estimates but I used my gas prices for this. It actually doesn't matter if your gas prices are higher or less cuz the difference between Reg and Premium us usually between $.25-$.30 so at the end it means your not saving as much as you think your are by using reg over premium..

vrferrari

Well, if it helps at all........it's the opposite with my GS4....

3.61 premium
3.41 regular

.20 price difference per gallon, average fillup is 16 gallons for me, so you're talking 3.20 more per fillup (or not quite another gallon of 87 octane).

Using regular unleaded 87 octane fuel, I can go roughly 320 miles between fillups....20 mpg

Using premium unleaded 91 octane, I can go roughly 350 miles between fillups....just under 22 mpg

The $3.20 I saved at the pump cost me 30 miles per tank of gas....remember, unleaded 87 octane at $3.4/gallon gets me 20 mpg.

Using this simple rule....you can see that using premium fuel in my car cost LESS per mile (barely) than using the cheaper grade of fuel.
In the end, the cost per mile is a wash so there is NO money savings in using 87 octane fuel at a .20 savings. I simply can drive further on my 16 gallons of fuel when using premium, which offsets the cheaper price of 87 octane, but requires me to burn in excess of 1+ additional gallons to go the same 350 miles

MJImport

iTrader: (1)

Good work guys, but from the threads I've been seeing about members' differences in fuel economy, I'm guessing this can change quite a bit from one individual to another. Basically just plug in your personal mpg into the equation to get your gain (or loss).

vrferrari

You usually see this type of drop, % wise, with most cars that require premium fuel.
The spark curve (and possibly the injector pulse ?) must be modified by the ecu to keep detonation from occuring. Detuning the engine in this way allows the car to run properly on the lower grade of fuel, but with less hp and torque the car is now performing less effieciently.