> Maybe not digital, but what about the analog MPG meters that BMW's have had
> just below the speedometer for as long as can remember.  I'm pretty sure
> these existed before FI replaced carburation on BMW's, maybe not.  Anyway,
> these meters respond very quickly to driving conditions.  Any idea if these
> used a flow gauge?
>
These, as do most "economy guages" use a pressure sensor on the
vacuum line of the engine. The harder the engine work the higher the
vacuum. Very imperic.

Nic