Bruuster

I use Shell 91 octane in my 2001 A4TQ. They recently advertized "V POWER" for this 91 gas. However, I seem to get 1-2 MPG better than before.

I know V is a detergent but if it was the injectors that were dirty why do I get worse MPG when I put in Mobil 91?

[ej257]

Could be due to the weather, etc. 5-10mpg, ok, now there might be something good going on, otherwise you're driving with a tail wind.

Bruuster

It's been really hot lately about 100 degrees. Do the cars run better when hot?

JAFO

but reduce power. also putting in a hotter thermostat will increase mpg.

dB

I drive my 4000 more or less the same every week. Most of the miles are the same 60 mile roundtrip to work 5 days/week. For some reason I've noticed 2mpg improvement over the last two tanks on V-power. However, I've been using Shell premium for a long time and when the advertising started up I really didn't notice anychange until the last two tanks. I've gotten 34mpg before but usually get 32. We'll see in the coming tankfulls if this V-power actually is consistently improving my gas mileage.

Audi4orce

One is oil refineries refine diffrent in the summer time. In a few words u get more gasoline in a gallon.
Second, Hot weather does increase the mpg. On start ups the ECU does not supply more fuel to stablize idle...and all that other stuff.

When winter rolls around, gasoline is formulated diffrent(makes the green people happy) thus u get less gasoline in a gallon of gas.
Second, cold weather makes engines use and waste more gasoline.

Also, in summer time u start your car and go..
In winter time...most people have a tendancy to let the car idle more. Many mornings i will run out and start the car, run back in side and forget that my car has been running for 5 minutes.
A gasoline engine idling uses a fair amound of gas vs a diesel engine that can idle for hours and use a few onzes of fuel.