whats the ave for this heavy 4 banger? i have seen 17mpg to 23mpg from all types of different sources....but nothing on what its supose to get stock?

playing with things i can get anywhere from 14mpg-17mpg......any input....new filter and pump oc mix is the only thing that changes it for me and it has to run real lean to get the 17mpg.
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Wie lange wird Ihr Auto leben?