Hey nice review. Im just gonna touch on the gas mileage thing.
The N54 doesnt like to be new. It burns gas, mine burned a quart of oil, I was getting worse mileage than my dad's 302 Merc etc.
However, after the 15K service that all changed, once you get past break in the car just gets that much better.
And it keeps breaking in. Over the subsequent 10K miles to 25K the car is still getting used to itself. Your mileage will keep climbing until that point. and then it wont come down.
I routinely get north of 30 and sometimes up to 35-36 MPG in my vert on the long drives from NYC to Syracuse.
This is an example from a few years ago
