sammy5001

My 2014 Porsche Cayenne reports MPG exactly as I measure and the range estimate is dead on (unlike my Q7 which always reports 500 mile range upon refill and dropping 10 miles for every 1 mile driven). However the Cayenne does not have the ability to measure AC power usage so I guess it "has no choice" but to lump all energy use together. The Q7 on the other hand has the option to separate them but to me it's just deceiving to do that though.

Brimstone

FWIW I'm less concerned about the range, with a 7 mpg spread between city and highway, over a 20+ gallon tank that's going to be 140 miles of range difference.

It would be nice if you configure the estimate in the MMI
1. best case (gallons * 25)
2. worst case (gallons * 18)
3. average (gallons * 21)
4. short term average (gallons * short term mpg)
5. long term average (gallons * long term mpg)

That would be easy and only marginally take longer to program than it did for me to type this post but oh well...

It just uses the 1st case, since it continually recalculates by the time the tank is near empty its going to be within ~7 miles. Although it says refuel there should be at least 1 if not 2 gallons left in the tank. I drove for 10-20 miles after refuel and put 20.88 gallons in the tank (tank is 22.5 gallons), so I think you can probably go very conservatively 30 miles, but probably about 50 max after you get that message.

sammy5001

#4 is the only one that makes sense to use. In other words, "if you keep driving the way you're driving, you will run out of gas in XX miles".

With all the wisdom and superior German engineers in Audi I'm sure they've all thought of those. Of course management would want to use the optimistic metric to make things "appear" good.

Also for #2 18mpg isn't really a worst case -- that's actually again the best optimistic ideal case for driving in the city. In "real city driving" I've yet to get >14mpg as reported by Audi's computer so probably 12mpg in real life.

Brimstone

well if I'm in traffic jam scenarios yes. its definitely < 18 mpg.

regular city driving (no more than 2 stops per light) I tend to be around 18 or so. And for #4 or 5, they will be inaccurate if your driving suddenly changes which isn't uncommon if you're doing city to long trip or vice versa (long drive to a city). Although #4 is probably the best default, at least letting the user choose their inaccuracy is better than a false optimism. (also the user can easily reset the #4 or 5)

Lookout57

FYI, I have a friend that works at a VW Group facility. He asked the Audi guys how MPG is calculated and they said the vehicle uses ambient temp, engine temp, throttle use, air pressure and other data points from all the various sensors and computers in the car. That said how they calculate is more sophisticated than a lot of other brands.

RickObe

It does seem that is how it works (#4). I have started out a drive with, say, 100 miles range. Drove 5 miles in city traffic to get to the freeway, at which point it says range is 95. Then after driving on the freeway for a little while, the range has crept back up to 110 or so.

Brimstone

I've had it creep back up once or twice but that was only after coasting a lot (and probably exceeding 25 mpg for several miles)

Once it stayed at 555 for like the first 50 miles or so after I filled my tank. But 555/22.5=24.6 mpg so I'm pretty sure it just takes gal remaining *25 to print that number.

Not sure how it measures gallons remaining but I know going up or down steep hills can give sensors false reads, could be another reason it creeps back.

Wisconsin Q7

Okay - I've "topped off" a few and done mostly whole tanks.......and the computer on the car is close enough.

This car does better than the Acura did and just as good as the Benz diesels.