Please give your average MPH as well as your MPG. Having an indication of what your avg MPH is will help better understand the type of driving situation you're in vs 70% city/30% highway.
Some city/urban driving contains lots of timed lights on boulevards/parkways where your avg MPH can be higher than some city/urban scenarios where there's a lot more stop-n-go situations from block to block. The higher your avg MPH...the higher your avg MPG will be. If your city driving has a lot of stop-n-go and idling situations, then your avg MPH will be lower which will in turn affect your avg MPG. But without knowing what your avg MPH is...its all speculation.
