Keep in mind, that's not the only size jump you can do. You'd probably start with a full charge, and so could drive a solid 3.5 hours before your first break. You're only limited to 170 miles if you stay just 30 minutes. Personally after 3.5 hours on the road I', looking for a food and bathroom break, which may take 45+ minutes, giving you a longer range for the next jump as well. Of course, you're more limited by where the chargers are right now, since it's not like there is one every ten miles!