How to get really, really, really bad MPGs

First, let me say that I am an experienced Prius driver. I have a ScanGauge and know the 4 warmup states, I have an EBH and my grill is blocked. My tires are at 40/38 psi. In mixed driving in the summer I have no problems getting 55 mpg averaged over 3 tanks. In the winter I rarely turn on the heat in the car unless the windows need defrosting. But look at this picture:



So how do you do something like this?

Step 1: Live someplace cold enough that it doesn't get above freezing for days on end (and sometimes gets to 0'F/-17'C).
Step 2: Live 2.4 miles from work, so the engine never gets to operating temperature.
Step 3: Go home or out for lunch every day, for more short trips on the odometer.
Step 4: Get a job designing railroad GPS equipment that requires occasionally road tests, the tests consisting of driving 10-20 mph with frequent long stops.
Step 5: Happen to do 2-3 hours of this testing in the worst snowstorm to hit our area for a year, so the tires were slipping and sliding, and the defroster needed to be running on high the whole time.

Driving conditions:

 

My next tank was 48.6, similar weather (except no snowstorm), but radically different driving - pretty much all longer trips, and speeds were mostly 20-60 mph. And on the tank above, I did manage to pull it up to about 33 before I needed to refill.