Hi TMC, TLDR: Charging now starts at 6mph and a reaches a steady 7mph on NEMA 5-20! Details, AKA why would anyone do this instead of a 14-50? * I don't drive much -- approx 150mi/week * It should be slightly more efficient (about 1/4 less time charging == less charger overhead) * On a NEMA 5-15 I was seeing 5mph. Plenty for my needs, but the 5-20 adds margin both for range and weather (preconditioning etc). * Our electrical panel was totally full, except for a well situated 20amp circuit (on a single pole breaker). For anyone debating what to do but with similar low-range needs, I'm pretty happy with the 5-20 Cheers!