I have a UK version 1997 E38(RHD) 728i and it is the third BMW I have owned. This one does not want to give up the location of its fuse box.
It is not behind the top of the strut in the engine compartment and I cannot see it in the boot (trunk) behind either internal panels.
It's got to be somewhere and I don't have a Bentley's yet (though that may only tell me where it is on the 740, 750 etc.)
Please, please, does anyone know where it is hiding as it is driving me mad.
Thanks in anticipation of sympathetic (or otherwise) replies.

One of the neat things about BMWs is how there is a similarity that runs thru the whole family of cars. Your 728i has the same engine that is in the e39 528i (M52 engine)...and the e39 also shares many of the same styling cues.

If you look at info for the e39 528i and how the engine and many of the electronics are set up...you should be able to extrapolate that info over to your e38 7 series. The info is also in the owners manual (if you have one).

Another problem you're gonna run into here is that most of us are in North America and we didn't get the 728i. So you'll fare a lot better if you do an advance search on the e39 forum for the location of the fuses.

From perusing their forum (the e39) I seem to remember reading that the front fuse box is accessed thru the glovebox (LHD)...when they open the glovebox, there are two white knobs they turn to open/access the fuses...so that would mean that your RHD 728i should have a fuse box somewhere below your steering column/behind the dash...and if you have the small glovebox on the driver's side...you may find it there.

The fuse box in the trunk is located behind the INSULATION once you fold down the battery compartment door there should be a fuse index right on the back of that door. Look for a slit in the insulation...fold it back and the trunk's fuses will be revealed. :)

http://www.bimmerboard.com/members/q/original/E38%20trunk%20fuses.JPG

Thanks again Q.
I'll have a gander when I am more awake.
Cheers. :drink1

Spot on Q.
I do indeed have three fuse boxes...one behind the boot insulation (which is where the cigar lighter fuse is) one in the lid of the passenger glove box, and the other in the top of the driver's small drop-down storage compartment. 10/10 for that one.
All fuses in the rear strip are intact and the cigar lighter is #52 fuse rated at 30A. The bank of fuses itself does not have any identification as to which # fuse is which to compare to the chart on the back of the boot liner panel but I know from the panel that is serves the make-up lights and the charger socket as well. The lights behind the sun visors do not work...but the charger socket (if it means for the BMW torch) does, so I am guessing the fuse is OK and the fault lies elsewhere.
I shall hard wire a switched supply from a 12V supply as planned, to power my sat nav and try to work out later why there is no supply to the cigar lighters themselves when my WDS arrives.
Thanks again for the help.

Great...you found them! :)

The fuses in the "boot" can be located using the diagram on the back of the battery compartment door. There are several things going on in that diagram. It indicates WHICH fuses are back there, their fuse nbr, their amperage, and their location within the fuse "bank".

If you look at the far right (the stuff in the rectangular boxes) of the diagram on the back of the compartment door...you'll see that it gives the "order" of the fuses in the bank behind the insulation...starting with fuse #49 (in my case...not sure if the 728i is the same)

Again, the fuse Nbr and amperages given in the rectangular box on the far right...gives the details of the fuse's location in the bank behind the insulation. :D

http://www.bimmerboard.com/members/q/original/e38%20trunk%20fuse%20index.JPG