[A4] Gas "Gauge"

[Robert King]

Just how flaky are the clusters?  If I replace mine, if/when will it
screw up again?  Mine's had problems for a long time:

- classic screwed up computer display in the center
- Air Bag warning light likes to flash randomly (I've never been able
to actually pull an airbag code from the airbag controller ot the
instrument cluster, so I presume the fault lies in the cluster
somewhere.
- Speedometer occasionally jomps a few MPH and immediately settles
back to the correct speed.  Never tried to diagnose this, so it may be
a transient condition in the speedometer sensor, or on the CAN bus.