I've found that it depends on the terrain, what speed you're going, and how well you use the regen brakes, and other power usage.
1. The battery drains VERY QUICKLY when going up even the slightest incline, and you don't get the equivalent energy back when you go down that incline. So, in hilly areas it drains about 2 to 3 miles of charge for every 1 mile of charge on the battery.
2. I've noticed that the battery drains disproportionally as speed increases, or so it seems. So, I get much better range if I do 45mph vs. 65mph. Because of this I actually avoid speeding because it just costs me precious range on the battery.
3. Using the regen braking as much as possible obviously makes a big difference. I try to almost never hit the brakes, but let the regen do all the work.
4. On the Tesla the A/C is about a 14% drain on the battery. Dunno if it's the same on the Karma, but it does cost a little. So far I haven't noticed much difference when using it tho.
So, on average, I'm getting around 41 miles on a charge (with the A/C off) and driving normally. If I avoid the highway and hilly areas I can get 45 miles or so.
-Brian