I'm pretty sure you have the mechanical system. If you have the Air filter on the intake side then it's mechanical or if you have the intake pipe running over the top of the engine to a filter on the exhaust side then it's an electrical injection.

I'm not entirely sure what your fuel milage should be, I haven't drivng that model long enough to see the consumption rate. Try asking a few other members on this board. It may also be listed in your owners manual

__________________
Alex.

MB Tech
Sydney, Australia
Volvo 122S
W201 190D 2.5 manual
W202 C240
W203 C32