sjd_boston

Just picked up a CPO car with 26k on it. Love everything about the car so far, but my highway MPG are around 21 no matter how I drive it. Dealer is saying that is normal. Even if i reset the short term display while on the highway it stays in the low 20's. Page 25 of my manual says the consumption page should display 4cyl mode under the bar when it is activated. I have never been able to trigger the message in 2k miles. Is it an error in the manual? Is my MPG normal? I may have just been spoiled by the belching 2012 Q7 TDI that they just did my buyback on. Not that is had close to the power.

sjd_boston

Meant Consumption screen, not page.

LexusLSguy

21 is a bit low. Driving style, road conditions / elevation, temp, fuel quality, all can play a factor. One of the first things I did was run about 6 - 8 ounces MMO in my fuel for maybe 4 tanks in a row when I got my CPO about 5 months ago. My favorite cleaner and lubricant for the fuel system. My mileage improved and so did the idle. Not that it was ever bad but I'm pretty **** about my car. I have the 3.0 but I am getting between 27 and 31 depending on how I drive. Your air filters are clean? You should be around 25 on the highway.

MP4.2+6.0

There is no "message" for four cylinder COD mode. Display just flips from white to green in color when mode engages. COD will likely only operate up to low 70's on level ground with a light and steady foot/cruise control. Heavy A/C or other power consumers may change/lower point it will stay engaged too.

Check MPG's on computer display vs. actual MPG by dividing trip meter miles by gallons pumped. Displays are usually off, and almost always optimistic. Thus, actual results for OP--or others--may be even lower. And I would not assume Q7 was accurate either, nor off by the same percentage for that mater.

dwboston

This is exactly how it functions in my 2015 A8 (NWB) 4.0T. There is no message (despite what the manual shows), the bar in the Efficiency screen turns green when COD is active.

tgomezS8

On a long road trip, driving for hours at around 75 mph, my car gets between 25.5 and 27.0 mpg, depending on how flat the terrain is. Keep in mind, that's what the computer says. I haven't measured it myself yet. This was driving in 90 degree weather with AC on all the time. EDIT: I run 45 PSI on front tires and 39 PSI on back tires.

L0U

I have had a few tanks go 600 miles on the pure highway road trips between fill ups. Things like wind direction for 8 hours, and gas quality makes a difference. A 91 or 93 ethanol free gas works wonders.
I run 40psi in tires.

DennisC

I have a 2015 A8 4.0 twin turbo. I get 28mpg on the road all the time. 31mpg if I drive no higher than 70mph. I turned off the engine cutoff switch permanently the day I picked up the new car. I think it uses more fuel and wears out the starter anyway. Just my personal opinion as an old mechanic. Please take note that you must use the gas brands in the manual. Very important to follow that rule, as i had major problems for 18 months using Sunoco's best premium. Turns out you need fuel with lots of detergent. I use mainly Shell premium and when not available Mobil or Exxon.

DennisC

Further to my above reply I run Pirelli P-zero's at 40 lbs. Also the car got 22-26 mpg till I broke through the first 10,000 mile mark. I was very mindful of breakin keeping staying at 3,000 rpm or less for first 1,000 miles and not over 4,000 rpm through 2,000 miles. I varied speeds up to 80 on open roads.

LexusLSguy

This is also why I add my own detergent. All the ethanol in the fuel makes it even worse. MMO not only cleans but also lubricates. Good stuff. Check out the UOA's on it if interested. When the engine auto shuts down it does not use the starter to restart. Just fires the cylinders waiting on that compression stroke. Pretty cool.