11 mpg?
The HT4100 is probably the least reliable engine to ever disgrace GM. But even it should be better than 11mpg.
I remember watching the primitive "travel computer" on the larger, ever so slightly more reliable 4.5 Cadillac. I could occasionally get the average to about 20 mpg.
The scrap value of the aluminum that makes up the block is probably greater than that of the engine itself as a whole.