Most public level 2 stations are wired with commercial 208V. That's if there is no voltage sag in the line run to the EVSE, sometimes you are lucky to see 200V at the EVSE.
A 3.6kw Charger on board is at 15 amps and 240V. Drop the voltage to 208 to 200V at the same amps, 15, and you are looking at 3 to 3.1 kw, before charger and battery losses.
Same factor with a 7.2 kw charger on board. You need 30 amps at 240V Residential Voltage, not commercial 208V. When running a 7.2 kw charger pack on 240V residential, the last 20 minutes of charging to completion will really drop the amperage charge take rate by the battery. The amount of miles gained in the last 20 minutes top charging is slow going, very little miles added to range for amount of additional time on the charger. Might wish to remember that on longer trips while waiting to recharge, and get back on the road instead, if you don't need the range to the next L2 charge station.
I can't comment how much if any a 3.6 kw charger on board slows down for the last 8 to 10% charge being added. I can say I've noted it with the 7.2 kw charger on my 2015 SEL. YMMV. Given a choice, on the road, if the price per kwh is competitive, I will always take a 240V NEMA 14-50 outlet with my own EVSE 40 amp box over a public 200-208V EVSE station. It makes a 17 to 20% difference in savings of time if I am on the road and need to get somewhere without waiting extra time before moving on down the road with a 95 to 96% SOC. When my Car-Net app says I have 15 minutes left to complete, I unplug and get going again. Too little KW added in the last 20 to 15 minutes.
If you are using a DC fast charger, you will see a charge to about 80% in 20 minutes, 90% in 30 minutes, if a 55kwh model, and a charge of 80% in about 40 minutes if a 24kwh version, and close to 90% in 50 minutes to an hour, like a ChargePoint 100, or Dc charging units you might see at a BMW dealership or a few VW dealerships here in California, or along the electric highway along US101 and I-5 north to the Oregon Border.