Thread: Sudden MPG increase

Were you always using 91+ octane?

the DIC likes to lie.

Originally Posted by GTLGDP

I've never used Lukoil gas before, so i was running low. Got some premium. Immediately on the ride home i went from 22.4 to 24.3. What the hell? Do some gases give you better mpgs? I heard Lukoil wasn't even that great of gas and i just gained these mpgs.

Lukoil is decent. I've used Lukoil, Sunoco, BP, and Exxon 93 with similar results.

Originally Posted by SJAndrew

The only variable that your can change to increase your MPG any significant amount is your driving style and or engine/drivetrain. Crappy gas versus premium, oil/fuel additives etc will only change your MPG within the margin of error.

I agree on the whole doing the math part of figuring MPGs over trusting the dic.

But there are MANY factors that can mess with your MPGs. CPS, Too hot or too cold of plugs, bad plug wires, bad coils, clogged fuel filter, bad or weak fuel pump, seized brake calipers, I could go on and on.

The DIC doesn't lie..it does the same thing a calculator does...distance divided by gallons=average MPG..how can it lie?

Originally Posted by SJAndrew

Those can all affect your MPG, but they're small and each and every one of them are trivialized by your driving style.

In other words: if you really want better MPG, drive like an old lady.

I will never discourage anyone from tuning, getting new filters, better plugs, better gas etc. But if the end-goal is better MPG, you're wasting your time unless you're also willing to modify how you drive.

You have to keep in mind, over 80% of people on this site don't perform regular maintnance other than oil changes. With proper maintnance, yes, only driving style is a factor, but most of the time, that is not going to be the case.

I also disagree on the "driving like an old lady" theory. Its all about avoiding stop signs, stop lights, and getting on interstates and highways as much as possible. Idling is a waste of fuel, but you can't turn the car off, because startup uses fuel, so run that yellow whenever possible.

The key as far as the car goes really is a proper Air/Fuel/Spark mixture on a well maintained car. Nothing more, nothing less.

Originally Posted by 4THGENCAMAROFAN

The DIC doesn't lie..it does the same thing a calculator does...distance divided by gallons=average MPG..how can it lie?

You are vastly over-simplifying how a car works. It doesn't know how far it actually traveled, but how many times its wheel bearing spun. Which can vary a good deal if your tire is the wrong size, bald, under-inflated, etc. This part of the car won't set off the tire inflation alarm until it detects (i believe) ~12psi under whatever it was set to. It's not sure the tire is under-inflated until that point, which lets you know just how imprecise it is. It doesn't even know how many gallons are in a tank, but merely how high the float is relative to the pump - which you already varies greatly by the vehicle's incline. So that's clearly got nothing to do with it.

I think the (most of the) rest is based on the front O2 sensor, but I'm probably wrong there... not something that's concerned me to look into in depth.

That being said, consensus seems to indicate that 04+ models are nearly spot-on while 97-03 models make something akin to wild guesses than calculations.

Originally Posted by Explicit_Spade

I also disagree on the "driving like an old lady" theory. Its all about avoiding stop signs, stop lights, and getting on interstates and highways as much as possible. Idling is a waste of fuel, but you can't turn the car off, because startup uses fuel, so run that yellow whenever possible.

Actually if you're idling for more than 10 seconds you're better off shutting it off and restarting it when you need to move.

back in the 80's my parents had a caddy eldorado, and it had a dic, with avg mpg and so on, and if it had 87 in the tank, and then you put in super, you would see a increase in mpg on the dic, higher octane should net a few more mpg.

so maybe the gas you usually get sucks, and the new gas has a higher octane,

think about this, the tank is full and still getting higher mpg, and a full tank adds the weight of 2 fat kids in the back seat.

this is why we race on a empty tank of gas. or under a 1/4 tank anyways.

Originally Posted by SJAndrew

A crude MPG calculation can be made using vaccuum and speedo

And how does your car calculate speed?