That was done without impeding traffic, too - I’m not about to be that guy.
About half was done driving around my area on short trips at 40 mph, the rest driving longer distances at about 60 mph. I avoided use of HVAC when below about 50 mph, instead rolling down the windows, which was usually enough to keep cool. Other than that, it was just gentle to moderate acceleration to avoid inefficient high-power or very low-engine-power modes of operation (most of the time, anyway - a few WOT runs did happen), gentle braking to harvest the most kinetic energy (most of the time), aggressive cornering, and going with the flow of traffic rather than aggressively pushing through it.
I wanted to try for the 700 mile club, but I simply don’t have enough fuel to safely do it. (I’ve gotten into the 700 mile club many times on my TDI, but then, in that thing, I had about 5.5 gallons more fuel to work with. And, with this percentage of city driving, the TDI would’ve struggled to get into the 600 mile club, even.)
Oh, and for those that prefer real units, that’s 3.90 l/100 km.