the mpg ratings are still too bias and "advertising" more so than factual information.

Last time I researched it, they still used pure gas for the test. Most states have at least 10% ethanol which robs efficiency.

Also the test for city driving is more like spread out suburb driving and does not include idling in traffic.

IIRC the cars are also fully warmed up etc, which is also not calculated into the fuel used for the test, but uses fuel in actuality.