After a proper LPG tune... I got 530km for 55L (10.4L per 100km) on gas for highway driving, with 290km with the A/C on. Before that was almost 15L per hundred on the highway.

Gas usage before the tune was 19.2L per 100km but will test over the next few weeks for new values.

This is a for 1998 Verada Xi, 3.5L. Venturi system LPG.