E93 Actual fuel economy?

[nola mike]

Looking at possibly getting an E93 convertible, as one of several cars that I'm looking at. It's one of the few 4 seat sporty convertibles out there available as a stick. So I've seen a ton of threads, but none have really addressed mileage the way I'd like to do it. City driving is too variable to make mpg much use to compare. The computer is always optimistic on every car I've driven. Also want to compare the exact car, which would be RWD, convertible, stick. So has anyone tracked their mileage on this car:
1. All highway driving (on a trip for example)
a) at what average speed?
2. By actually calculating the mileage: Fill up, drive x miles, fill up again. That's the # of gallons used during those x miles.

Would love to have some objective info.

[White94RX]

First question, is what engine? N52, N54, N55? The 54 and 55 and turbo engines and will likely get a little less mileage. I had a 525 with an N52 for a few years. It's probably similar in weight to the E93. I would get low 20's around town, and mid to upper 20's highway at around 75-80 mph.

[Codes2]

My answer isn't exactly what you are looking for. None the less, it may have some value...

I have a 2008 335i N54 E93.
I found it very close to gas as my 2008 335xi N54 was, approx 9.9 L/100km. (both twin turbo)
Once I modified my E93 N54 by pushing the boost to double, and driving more sporty, I'm now around 12.5 to 13.0 L/100km.
In both cars, my average speed (per car readout, reset each fill up) is 49 to 55 kmph. I'm half highway, half city (by the minute, not the distance)

My 2010 E92 (sports wagon, naturally aspirated) averaged 9.3 L/100km, similar to my 2001 330i. (both unmodified, N/A motors)

I use the computer and separately a calculator to monitor my L/100km. I found them as close as 1% and as far as 3% in similarity. (unlike a 2003 Saab 9-5 I owned which had a significant difference)

[davidwehr]

1.28 mpg
2. 70 mph
3.never calculated that way - just used computer. Avg. MPG is 22 MPH. Not bad for how I drive for fun.