I tried it I got as far as


Instructions to access the hidden OBC functions:
1. Hold Trip Reset while turning ignition key to on position
2. OBC should show "Test"
3. Use Trip Reset to select function 19.0 that unlocks all the features
3. Wait for display to show "Off"
4. Depress Trip Reset for 1/4 second and release it
5. With no delay press Trip Reset several times to select one of the following functions.

But didn't get the option to select 7.3

Select 7.3 + Vehicle speed / Current Speed in km/hour

I also somehow reset the service indicator. It was due for oil service in 9000 miles. Now it shows 15,000 to inspection. I can't seem to set it back to how it was! Not really a problem as I've noted the mileage and will just get the oil sevice done when needed.

Be careful if you don't know what your doing! (like me)

A quick google revealed

http://www.autoshoppingcenter.com/servicelights/Bm...

&

http://www.launchtech.co.uk/documents/BMW%203E46_s...

I always thought that you could only do this with special tools. I suppose if looking at a new car it would pay to check paper work/receipts thoroughly.