Buying a cheap DD with good gas milage

in the next couple of weeks im planning on buying an 88-91 Civic hatch!! i see them all the time for 1-2k in good condition. I've always like the look of them i also want it to drive to school becuase people are always gettin there car broken into, so i hate drivin the stang and benz. Im also looking forward to the great gas milage. Neways i also had my eye on some 87-92 Cadillac devilles, but they only come with v8's like 4.1L i think.. neways does ne one no if the caddy v8's get any good gas milage? if not ill prolly stick to the civic and throw a fart can on it just to be funny lol