1. Whether the trip is possible. You need enough range to span the largest gap between charge stations with an acceptable safety factor.

2. The number of charging stops you will need.

Charging speed determines:

1. How long your charging stops will last.

Trip time is the sum of:

1. Time actually on the highway.

2. Time actually charging at your charging stops.

3. Time transitioning from #1 to #2 and later back to #1. Let's call this overhead time.

The total time spent actually charging is, assuming you started the trip fully charged:

  (Trip_Length - Range) / Charge_Rate

For long trips the time spent charging is usually much more than the overhead time. A fast charging short range EV will usually get there faster than a slow charging long range EV.

Anywhere where you don't have access to your own charger, being able to add 100 km of range per minute, makes it possible to make the switch to an EV.