You didn't specify how much you travel in a year, but based on your daily route, I'd say around 15,000 Km in a year.

For your E-150:
(15,000 Km) / (3 Km/L) = 5000 L consumed in a year
5000 L x 30 Php/L (please correct me if this isn't the price of LPG) = Php 150,000

For your Everest/Hiace
(15,000 Km) / (8 km/L) = 1875 L consumed in a year
1875 L x 45 Php/L = Php 84,375

The only time the E-150 will be cheaper is if LPG only costs 16 pesos.