I think the Mile-O-Meter was designed to help the driver improve his driving skills to increase the drivers miles per/gal. I don't know when this was out as a product but I would guess late 50's early 60's. Of course it is a very good vacuum meter and has a large scale to detect leaky valves and other vacuum related issues. I will have to pay more attention to vacuum readings next time I tune my old engines. All that has been discussed makes good sense to me.
Thanks, Chet...
Thanks, Chet...