the car (at least mine, a 2wd 85) assumes 300 wH/mile (Watt Hours) per mile.
you can tell it to display this, which is the EPA rated milage, or you display the other one. lol, I i think the other option is ideal, although I consider rated ideal.
If you drive 'normally' with traffic, it's not that hard to hit 300 wH/mile. if you drive like me you'll be around 320 or 350. (heavy foot off the line).
Cold will also impact range.
With the 85, I've only ever been concerned ONE time driving. and It was mostly my fault for driving 230 miles from one super charger to home, and skipping a charger along the way.
I partially blame a Nissan GT-R I was pacing around Ocean City, MD.
The car will tell you how much you've used over the last 5,15, 30 miles, and I've gotten up to almost 2,000 wH/mile when playing in the mountains of PA.
In any case, my daily commute is under 40 miles, and I start each day with a 'full' charge.
One of the things they don't really tell you on the site is that you'll start each day with a 90% charge. Not 100%. this keeps the battery happy and reduces wear on it.
I've had no range issues, and LOVE my car SO much, I want another! (P85D next time).
The thing you have to realize, that many who move to an electric car don't seem to fully appreciate, is that you start
every day with a 'full tank'. You don't drive out of your way to the gas station whenever you want. You just go home to work to home to charge. Range isn't an issue when you wake up to a happy charged car