"As readers might recall, a new record was established last month by one enthusiastic Model S owner, who drove a painful 24-miles-per hour to make it a stunning 452.8 miles on a single charge. (The car is advertised as having a 265-mile range.)
Musk didn’t elaborate on whether someone would need to drive just as slowly to reach 620 miles in 2017. We’d guess that’s not what he had in mind, though."
"1000 kilometers... hmm. Well, it depends under what circumstances for a thousand kilometers. As it is, the record right now for model s is 800 kilometers (496 miles). That's the furthest that anyone has driven a model s. ... Now, in order to do that, they did drive at a relatively slow speed, so, you know, we're talking, I think they drive at 40 or 50 kilometers an hour (25-30mph) or something like that. But I think, my guess, we could probably break a thousand kilometers within a year or two. ... 5 to 10% a year"
It seems, to me, slow driving ("circumstances") is what he had in mind.
That's commitment.