Winter Cabriolet

I have a 2018 2.0 q5 with about 56,000 miles on it. On long trips on the highway I usually get around 28-32 mpg. My speed is usually 70-75 mph. Last summer I took a 1000mi trip, and was getting my normal mileage. We stopped for a sandwich (1/2 hr) and got back in the car to continue. When we took off, I noticed that after 10 minutes or so, the avg mpg was heading down quickly. I pulled over, restarted the car and the mileage went back up. This has happed just 3 or 4 times since last summer. This morning while on a cross country triip it happened again but I at first blamed it on 10F temps and high winds (and 80 mph speeds)The mpg was 21 mpg. I pulled over, restarted and the mileage quicklly went up to about 27 mpg. Not bad for the speed and weather. What's going on????? I know that if I take it in they will say that they could not find anything. Thinking it over, some sensor is telling the engine that it's not fully warmed up yet so it needs to run a bit rich. Coolant sensor??? or??? What do you guys think?

ribeye

It might be the mpg computer and not your actual mileage. I generally do not trust the accuracy of those things anyway. But, thats me.

Sandroad

It’s just the guess-o-meter that recalibrates each restart. It’s averaging for both trip and long term mpg. You mentioned high winds and high speeds on one trip and both of those will both whack mpg because wind resistance goes up as the square of the speed. There’s nothing wrong with your Q5, IMHO.

Winter Cabriolet

I have seen the gas useage increase substantially watching the gas guage drop when in the high useage mode.

epikdj

driving against wind does drop your mpg significantly than if you drive with the wind pushing you forward.
additionally I have noticed, using cruise control, heated steering wheel and heated seats affect the mpg

Wires

Any hard acceleration, etc will cause a substantial decrease in the dash displayed mileage since it's using that to predict your actual MPG. Once you drive normal for a while it should straighten out, but keep in mind what you see on the dash doesn't 100% correlate to what is coming out of the tank. It should be "close" at the end of the day over the entire tank, but mine always reads higher than actual since it does remove those hard accelerations from the average MPG after you drive nice.

rockdoc

Based on 35,000 miles on my '21 Q5, the MMI reads an average of +1.4 mpg over the true value, with differences generally ranging from 1 to 4. The difference was seldom negative. The average mpg over the life of the car is 29.1, with a high of 36.1 on a full tank (I've had higher values on portions of a full tank, e.g., 3-5 gal). Around-town mileage is generally in the mid to upper 20's. Observed low mileage was generally in poor conditions (e.g., snow storms), on partial tanks (fill-ups of a few gallons), and head-winds or cross-winds caused a 3-5 mpg drop. All of this was with Top-Tier premium gas.

4ringsnewbie

TSB