ive got a 1985 2.5 n/a stationwagon 90... the other week i was coming back from bodmin. the light does the aformentioned on/off roaund corners and up hills. when i got onto the M5 i carried on going till the light was solid and didnt flicker. i must have done only about 20-25miles. the neddle hardly moved! i pulled in and filled to the brim. it took 47.55l. i believe the tanks on 90 SW are 45l so i musta been freaking low! i guess the extra is taken up in the filler pipework and neck as it is nearly 3" wide.
G