With different injectors and lots of tinkering with Fuel / Airflow / Throttle settings I now have a tune I am more or less satisfied with (HHR 2.4, 2008, no flex fuel). However the average/instant MPG values as shown in the instrument cluster are now markedly lower than the real-world consumption.

How can I compensate for this deviation? I saw a number of forum posts mentioning something like "Instrument cluster" under Engine / Fuel / General. But I have nothing like that, only Stoichiometry, Injector Control and Cranking Fuel. Using VCM version 5.0.4 with View set to Advanced.