I've found diesel engines and vehicles to be considerably more reliable and therefore less expensive. Fuel is between 5-7% more expensive here in the UK so things are good there.

The city driving numbers are about the same I found. I regularly drive right into London's congestion charging zone - at least 1-2 times a week.

51 is the expected MPG in city driving scenarios. I can achieve that with no particular effort in London traffic. I don't drive like a crazy person and hang back regularly - that is all.

My vehicle doesn't have piles of expensive electronics, batteries and things to go wrong either (look at recent threads about Toyota stack overflows for example).

The most expensive thing on a Diesel that can go wrong is the particulate filter, EGR valves and timing chains and these are cheaply regenerated and replaced respectively.