I wouldn't agree with you... 2.0 is a small engine..
I think that you had a bad engine management system... I have 2litre, mid-big turbo engine and with VEMS on LPG (witch has less miles per gallon that gasoline) with 40litre tank I have passed 420kms, and still running... It was used 100km on fast road, 200km on outside city road, and the rest in the city on local roads... I the city, with a lot of rush ours and waiting, it spends around 13L/100km LPG with some boosting... On the roads outside the city, it spends as low as 7-8L/100km... My brother has small engine 1.6 with 100HP in nissan quashqai and it spend more LPG than mine 240HP-LPG lanos...
It's all in the EMS-EFI...
