Heres another calc, because Im bored
Say you want to keep a car for 8 years, and you drive 15 K a year.
You buy a new civic for 15 K, sell it 8 years later with 120K on it for at least 5K. You average 29 mpg, so you pay about 15K for all the gas you put into it. Total cost = 25K.
You buy a hybrid civic for 23K, sell it 8 years later for 3 K because that batteries are about to die. You average 42 mpg, so you pay 10K for all the gas. Total cost 30K