Home    Search    Gallery    How-To    Books    Links    Workshops    About    Contact

BMW 540i MID OBC Navigational Computer

back to BMW 540i page
back to page index

BMW E39 5-seried MID computer

BMW e39 5-Series Computer


The center dashboard of the BMW 540i has either a complex and outdated GPS navigation system or the standard and complete onboard navigation computer shown above. Both of these are located in the same place as the radio and share its controls and buttons.

The computer (MID) and radio actually are in different housings behind the dash. The CD and the radio share the same housing. The housing for the MID sits below its display. The MID is really a clearing house for information from other parts of the 540. Inputs to the MID come from the instrument cluster, phone, audio system, HVAC etc. Many of the MID displays, like the clock, can be duplicated on the instrument cluster.

The only thing I can recall that the MID doesn't show are idiot lights from the dashboard's "Check" module like LOW OIL.

GPS Satellite Navigation System

I chose not to order the expensive and optional BMW GPS system. It's identified by a big LCD panel.

I find it confusing and it requires me to divert my attention from the road just to operate the radio. I consider permanently installed car GPSs as obsolete as the old car-mounted cell phones for exactly the same reasons.

I prefer my modern pocket-sized Garmin GPSmap 60C for street navigation. I dislike the old-style bolted-in GPS because it requires you look at the LCD for many basic radio operations, and that modern GPS systems from standard suppliers like Garmin are easier to operate and update. With BMW you're a slave to buy map updates from BMW, which probably cost more than an entire new pocket sized GPS. I paid less than $500 for my pocket GPS system complete with maps, and, just like my pocket cell phone, my pocket GPS goes with me in every car, bicycle and airplane along with all my saved favorite data. My pocket navigator only cost $75 to upgrade the entire USA's maps and data for 2006, and upgrades come out every year.

Standard Onboard MID Trip Computer

Unless you drop a few grand on the optional GPS system above, all 540i come with a center console computer. This computer is located in the same housing as the radio.

BMW calls this computer the MID, for Multi-Information Display. Others call it the OBC, for onboard computer. Others call it the trip computer or navigation computer. It's all the same thing.

It even can calculate and tell you when you will arrive at your destination.

The computer in the 2002 Saab 9-3 is far easier to operate with only four buttons. The BMW 540i computer does a little more, but is far more complex to operate with more buttons with multiple functions for each button.

The standard BMW 540i computer calculates just about everything involving time, speed, distance and fuel. The instructions are all in your owner's manual.

Time, Stopwatch and Calendar

The clock knows the time, date, month and year. It doesn't know the day of the week.

The stopwatch has four digits. It reads in tenths of seconds up to a minute. It reads in minutes and seconds up to an hour. It reads in hours and minutes up to 99 hours and 59 minutes. I'm still waiting to see what mine does when I hit 100 hours. I'm only up to 88 hours so far.

The stopwatch stops when the 540i is turned off, and starts again when the car is restarted. Thus it will measure hot hours when making a long trip.

Personally I find it much easier to use a real stopwatch. The MID's multiple function buttons require me to look at the display to operate the stopwatch, and they aren't labeled with intelligent START, STOP and RESET. Instead the MID offers you SET and TIMER buttons. Good luck.

Automatic Ventilation

The BMW 540i can be programmed to turn on the car's ventilation system at any time you like. You can program two different times! Thus if you know when you expect to return you can have your 540i all cool or warm for you. It doesn't start the engine: it just turns on the fan.

Also the fan can be set to run for a half hour after you've turned off the 540i. This keeps the 540i comfy after you've left and turned it off.

Hourly Reminder Signal

It can be set to beep 15 seconds before each hour to remind you in case you want to listen to top-of-the-hour news broadcasts.

Enforcement Immobilizer

One may program the MID to require a code be entered to start the car.

This is part of the enforcement package which is standard (but not called out) on all 540i for securing prisoners.

If a prisoner or other unauthorized person gets your keys he can't drive away.

Speed Limit

You can program the car to beep and blink to let you know you're going faster than your preset limit. Set it to 45 MPH on your wife sometime, hee hee. Sorry, it doesn't actually limit the speed of the 540i. Default is 90 MPH and OFF.

Trip Navigation

You can enter the number of miles to your destination. The computer then calculates, based on your speed, when you will arrive. It is accurate, of course depending on the correlation between your past speed versus what your speed will be for the rest of the journey. I find my pocket GPS more accurate because it also knows the route I'll be taking and can estimate future speeds.

Average Speed

This calculates your average speed since the last reset. It appears to agree with the overly optimistic speedometer which reads 6% high.

RANGE xxx MLS or Cruising Range or Distance-to-Empty (DTE)

This is how much longer you can go. It bases this on how much fuel you have left and your recent consumption. Press the RANGE button to see this.

It's displayed as RANGE xxx MLS (or RANGE xxx KM).

The book says you have 1.8 gallons left when it says zero. The book also suggests you refill before it reads 30 miles, since you might start sucking some air and damaging the catalytic converters. My dealer told me it was OK to try this, just don't keep doing it.

As an experiment I ran it down to zero. It then went from RANGE 0 MLS to RANGE - - - MLS (dashes instead of a zero). I then filled up, and squeezed 19.077 gallons into my 18.5 gallon-rated tank.

I have no idea just how far it would really go after that. I tried this by going in circles around a gas station to see what would happen. Let me know if you play with this and really run it empty. I'd love to know just how much it might hold.


You have two separate computers for fuel consumption. They are simple; reset them with the SET control and they keep score. Many people never reset one to give them the lifetime MPG and reset the other for each trip or tankful. Do as you please.

Few people use these computers at all. It's not uncommon to be able to read the same value in both sections which will be what the car has gotten since birth.

My computer seems to be about 6% optimistic. We'll see.

Center Dashboard Repeater

You can choose which of all these displays can be called up on the center of the driver's dashboard. You press the left stalk inwards to cycle through whichever displays you've selected.

Just press and hold stalk's butto until you see PROG on the display. Not hit each of the displays you'd like to see, in the order you prefer, and then SET. You'll only get what you want.

If you want to have them all come up again as the car originally came, press and hold the left stalk button until you get PROG. Now just press SET.

Next Page: Performance Modifications

or Previous Page: Xenon Headlight Conversions and Upgrades

or back to BMW 540 index page

Home    Gallery    How-To    Books    Links    Workshops    About    Contact