I am getting around 25 mpg and have had to fill up 3x since getting the car about a month ago..... I think a better description is a fuel efficient electric motor run 2L turbo that has some electric range to it.
Interesting, since I have had my car for 11 months and have also filled it up just 4 times. And I have gone almost 4000 miles. You see, I drive about 35 miles a day when I do drive, and I plug it in every night. My MPG is an irrelevant number (something like 100 MPG). The point is better made that when I drive 35 miles, then plug it in, it costs me about $2.50 to go that 35 miles (at $0.15/kwh electricity costs). With gas around $4.50/gallon, my fuel cost per mile driven on electric is not quite half, so my "cost equivalent" MPG is more like 65 MPG. I have been on longer trips, and when I go to gasoline mode, I don't expect 45 mpg. This isn't a small econo car.
Clearly, the way you describe the car (a gas engine with some electric range added) is EXACTLY the way you use it. You say you drive 20000 km/year, meaning 1666 km a month, or about 1000 miles per month. If you have filled it up 3 times in your one month, as you say, then you have used probably 27 gallons of gasoline (the Karma's tank only holds 9.5 gallons of gasoline). That would suggest 1000/27 = 37 MPG. But you say 25 MPG so it must be that you drove less than that 1000 miles on your 3 tanks of gas. In any case... let's say 25 MPG. My wife's Lexus LS460 gets about 18 MPG, so you are still doing ok relative to large 4-door sedans. Not that MPG in that range would be a reason to specifically buy a car. But it wouldn't be a reason to DIS-like a car either.
More importantly, your driving results suggest to me that you have almost NEVER plugged it in. If you drive 1000 miles a month, as you say, and if you had plugged it in each night at your home, you would get 35 miles or so of range each day. Multiplied by 20 work days you should get at least 600-700 miles of gasoline-free driving...with the other 300 miles on gasoline (at 25 MPG, you would only then have used 10 gallons). If you NEVER plug in an electric car that is designed to run on electricity as it's MAIN fuel source, then of course you will be disappointed in the outcome. Then you are driving around a 5000 lb car whose extra 1000 lbs in batteries and generators aren't doing you any good. Nobody ever said this car would delight you with it's gasoline-only mode. It's designed to be plugged in.
So I don't fully understand your math, but I am challenged and maybe I am missing something? Like maybe a couple very long-range trips you took, or that you take regularly? E.g.: if your 1000 miles a month comes from Five discreet 200-mile trips, you only get to plug it 5 times, and you get 175 gas-free EV miles. The other 825 miles come in gas mode. But if someone else's 1000 miles comes in increments of 20 discreet trips of 50 miles, the result is very different, or in 30 trips of 33 miles, again very different. MPG can range from 23 MPG (never plug it in) to infinite.
In PHEVS, more so that in ANY TIME IN THE HISTORY OF THE AUTOMOBILE: your mileage will vary.
Oh, and you all know my answer to the poll: This is one of my favorite cars ever owned. I absolutely love it.