> A combustion engine converts less than half of the chemical energy in the gasoline into mechanical work that can move the car.

Much less. Your typical gasoline IC vehicle converts maybe 1/4 of the chemical energy into work.

The average Brit drives under 20 miles per day. A Tesla will do 4 miles per kWh, meaning it requires 5 kWh per day. That's 1/8 of 40 kWh. I'm not sure where the discrepancy is.