My average is 23.5MPG of mostly highway, but with heavy traffic, driving.

The biggest 'horror story' is annoyances related to diesel in my area, such as:
a) it's more expensive than premium
b) it's not available at every station, and even less if you're looking for 45-47+
c) most diesel pumps are dirty and many have big nozzles that don't fit (I don't want to use the adapter as it means a smelly thing in your trunk from now on).