Toyota Prius which gives ~ 40 miles per gallon [ source] Total gas consumption = 375 gallons Total gasoline expense = 1775$ - let’s take this as our base fuel expense BMW 3series which gives ~ 20 miles per gallon [ source] Total gas consumption = 750 gallons Total gasoline expense = 3750$ Extra expense over Prius = 2000$. Toyota Corolla (which gives ~ 30 miles per gallon) [ source] Total gas consumption = 500 gallons Total gasoline expense = 2500$ Extra expense over Prius = 775$ Note: not to forget that Corolla is ~ 7000$ cheaper than Prius Ignoring discounted cash flow analysis, It takes roughly nine years for Prius to pay back the extra premium.