OT: A question about car petrol consumption

[neutronics]

Really sorry I'm posting this but I thought I could get a quick and simple answer/explanation from this.
Is it true that a car on full tank petrol will get more mileage per litres of petrol from the same car that are not running on full tank?
Please explain if you drivers know about this.

 

[offshore80]

There are to many variables to form a true calculation. But, IMO the more fuel on board the more weight the vehicle has to haul. Which means more Horsepower to move the extra weight which would burn more fuel to start, stop and maintain speed.

 

[escape2thewater]

Cant say that i've heard that one before either...sorry but I have heard wierder things!

 

[searcher]

Don't know if this matters or not. I'm pretty sure that a tank that's low on gas makes the fuel pump work harder. Maybe that decreases mpg.

 

[plum70rt]

all I know a full tank of leaded 115 octane gas is SWEET!!
God Bless America and big blocks with mutiple Carbuerators
Who cares about MPG

 

[mattnc]

Originally posted by plum70rt
Who cares about MPG
Yeah, what he said...
The difference (if there is any) in mpg would be too small for you and your wallet to notice.

 

[neutronics]

Thanks all for the replies. Guess it didn't really matter even if there is any difference. As long as the car can cruise the highway!

 

[neutronics]

Another thing..taking a balance between offshore and searcher response, perhaps a half-full tank would be great!

 

[broomer5]

I don't know either.
Here's my guess.
Not full tank = better mileage in town, city driving where you start and stop often ( versus a full tank vehicle )
Full tank = better mileage on freeway, highway driving where you maintain a more constant speed.
More mass, more inertia.
( versus a not full tank vehicle )
I do know that you get more mileage from a gallon of gasoline then a liter of petrol

 

[offshore80]

Carburators left in the 80's. Now a days most of your fuel delivery is done with an electric fuel pumps. So once again I would think it's only a weight issue. Now, The lower the fuel level is in the tank the more condensation in the tank which lowers your octane and reduces engine performance. Hence worse MPG. So, if it's full with gas... Better performance but more weight. If it's low on gas less weight but more condensation... Err.. ahhh... Damn, The higher the octane the more efficient the engine will be so If you use higher octane you will get better MPG. Which will offset the expense of the fuel. Lower octane less efficency worse MPG. Damn, what was the question again? Shoot, I have a new HEMI and all I get is 11 mpg so my tank doesn't stay full long. It's always on "E".

 

[broomer5]

with or without a tailwind ?