If you have a continual load of 20 kW for 1 hour (20 kW * 1 hour), you'd have used 20 kWh. 20 kW * 3 hours --> 60 kWh. Multiply the units and values.
If you had a 100 watt device * runs for 1 hour --> used 100 watt-hours or 0.1 kWh. 100 watt device * 10 hours --> 1000 watt-hours --> 1 kWh. Also, you'll notice on your electric bill, you're billed per kWh.
If you're in the US, demand charges residential bills are rare but if you had them, those are in kW. You'd get billed billed both for energy (kWh) and demand charges (per kW).
I don't recall the power level you need to maintain 60 mph on level ground, but let's say it were 20 kW (it's probably a bit less). In 3 hours, at 60 mph, you'd have traveled 180 miles...
Notice that the EPA range ratings on Leaf Plus are a bit over 200 miles: https://fueleconomy.gov/feg/Find.do?action=sbs&id=43665&id=43666. Also, 1 hp is ~746 watts. 160 kW -> ~214.5 hp. In some places of the world, they will list engine specs (even for ICEVs) in watts or kW instead of hp. Also, sometimes, I've seen them in PS (https://en.wikipedia.org/wiki/Horsepower#Metric_horsepower_(PS,_cv,_hk,_pk,_ks,_ch), aka German Pferdestärke).