Gas Mileage and Idle

[VanillaGorilla]

First let me say that i plan on going back to the dealer and sitting in another R Spec but i will not be able to do that until monday. I was just wondering if anyone else has experienced any of my issues.


The first issue i am having is that my gas mileage seems to be getting worse. I have never gotten about 21MPG (this is according to the computer). My wife drives the car 90% of the time and it is mostly city driving. I have driven it to work (35 miles each way on the highway) and this is when i got the 21 MPG. Last night i drove the family and noticed that the car computer was averaging 13 MPG. I know that my wife doesnt have a lead foot. I will be calculating the MPG the old fashioned way but until the tank is empty i wont be able to get the full picture.


The second issue is that at idle the car seems to have a slight vibration. I am not talking about the clicking from the engine. Sitting at idle with my hand on the shift knob i feel a slight vibration. I do not recall feeling this before.


Car has 950 miles on it. I have been using the same gas station that i have used for 6 months on my other vehicles and have no issues with those. The car was averaging about 18 MPG in city driving. Just trying to see if anyone else notices the vibration at idle or is getting similar MPG numbers. Thanks.

 

[Skywagon]

Vanilla,
Have 2000 miles on mine now, get 16-18 mpg around town. 18 if I'm very careful and make a few traffic lights. Since my average speed around town is 17 mph I'd say that's fairly good. Just did a 600 mile road trip. Average speed 68 mph. A lot of cruising at almost 80 mph. Got 24.6 mpg according to the computer. I am running non-ethanol 93 octane. Maybe that's helping a little. I have noticed a rough idle once or twice but not in some time now. There is a lot of junk gas out there. Could that be it? I was told that a big box store was selling gas with 22% ethanol in it.....yikes!!

 

[Tin]

I have 2010 v8, we took a road trip and put around 1500 miles on the car. In some city we have better gas mileage than other. I filled with Shell once, and I got around 29 to a gallon on high way. this is running on 89. So it might varies between gas station and gas type.

 

[Dragon64]

First let me say that i plan on going back to the dealer and sitting in another R Spec but i will not be able to do that until monday. I was just wondering if anyone else has experienced any of my issues.


The first issue i am having is that my gas mileage seems to be getting worse. I have never gotten about 21MPG (this is according to the computer). My wife drives the car 90% of the time and it is mostly city driving. I have driven it to work (35 miles each way on the highway) and this is when i got the 21 MPG. Last night i drove the family and noticed that the car computer was averaging 13 MPG. I know that my wife doesnt have a lead foot. I will be calculating the MPG the old fashioned way but until the tank is empty i wont be able to get the full picture.


The second issue is that at idle the car seems to have a slight vibration. I am not talking about the clicking from the engine. Sitting at idle with my hand on the shift knob i feel a slight vibration. I do not recall feeling this before.


Car has 950 miles on it. I have been using the same gas station that i have used for 6 months on my other vehicles and have no issues with those. The car was averaging about 18 MPG in city driving. Just trying to see if anyone else notices the vibration at idle or is getting similar MPG numbers. Thanks.

You mentioned that your wife does 90% of the driving around town

Take the car out on the highway -with some good gas ( 93 octane )
and take it for a spirited long drive - blow the carbon out of the engine

then see how it drives afterwards

Bet it drives just fine

These cars are meant to be driven on the open road
not putting around town all day -

If you happen to have the wider tires on the car - 245/45R19 apposed to the 235/45R19's - your gas mileage will drop slightly .....but only slightly

Remember my friend

you've got a monster 5.0 under the hood
believe me - the car doesn't want to drive 3 miles to shoprite every day

Now get out there and hit the highway
the car will thank you

oh....one more thing : Pick up a K&N air flilter on line ( get the cleaning kit and oil with it - you have to clean and re- oil the filter from time to time )

Your gas mileage should improve a little

 

[VanillaGorilla]

Well after driving the car for a day or two after the most recent fillup my computer now shows an instant average of 18-19 MPG. No idea why the MPG shot way down. I also tested another R Spec at the dealer and the vibration at idle was noticeable. I guess i am just being a paranoid new owner.

 

[Dragon64]

Well after driving the car for a day or two after the most recent fillup my computer now shows an instant average of 18-19 MPG. No idea why the MPG shot way down. I also tested another R Spec at the dealer and the vibration at idle was noticeable. I guess i am just being a paranoid new owner.

I'm averaging around 20 mpg between city/ highway

I recently got 25 miles - highway only after about an hour of solid driving

not too bad I guess

Gonna take her on a long trip - and see what she will do

already - the 5.0 R Spec is beating my 330i ZHP with the straight 6

I never got more than 21 miles to the gallon in that - and that was on my cruising days - usually I saw around 19-20 with some spirited driving.

still want to put the magnaflow catback on in the spring -

car is holding up nicely

 

[timc1475]

When driving sedately via hwy I avg. 24-25mpg @ 70mph. When the foot gets heavy and the fun factor increases so does the consumption.

At idle, still smooth as a hummingbird here as percieved through steering wheel touch (after warm up of course). I only run the best gas which when figured at the pump is only a few bucks more than reg. at fill ups.