I once had this 68' Caddillac with a 472cid motor. and only 40k miles on it.
I put a 850cfm double pumper on it, at 45mph when I floord it and it downshifted it would break the tire freee in the rear and scare the crap outta me...that car was a beast!
Then I lent it to a friends wife for a weekend and it came back running on 6 cyl
Ended up junking it 6 months later when it took 2 quarts of oil every 50 miles of driving and was getting 6mpg
I am always sad when I think back on that car..it was in pristine condition..