You might double check that.  On my 2003 530i (same engine as Z4) service
and warrantee handbook there's a page (page 8, right below Insp II list)
that lists brake fluid (2 yrs), cooling system (4 yrs), O2 sensor (100K),
Spark plugs (100K), M-mobility System (3 yrs) and Auto trans service (100K
... was "lifetime" on 2001 cars, nothing changed except BMW reevaluated the
wisdom of "lifetime" fill).  The next page has a chart that has blocks for
service performed entries which includes those items.

I would also suggest the diff, trans and p/s fluids be changed at regular
intervals.

I strongly recommend you check the pre-free-maintenance service schedules
for our cars.  They're more conservative and likely to contribute to better
long term service and reliability.

R / John

Not necessarily.  My 2003 Z4 maintenance schedule includes no coolant
changes - it's "lifetime"!

Tom K.

Not unless the float keeps trending downward.  I'd have it topped off and
check the level every day or so for a couple weeks to make sure.

If your car is in the U.S. you might still be in the 4yr/50000 mile free
maintenance schedule window.  Your dealer will top it off for free.  Or you
might DIY.

According to the service schedule, your car should have the coolant drained
and refilled at 4 years from date of manufacture, that might be about now.

R / John

The owner's manual for my 2003 530i says that the proper coolant level
is when the upper edge of the float is even with the top of the filler.
Mine winds up about about 11/2 inches below that, but the temperature
gauge doesn't register any overheating on long trips.

Is this any cause for concern?

Thanks,

Ambrose