According to this source[1] an endurance horse riding 100 miles per day requires 78,800 KCal of energy, which translates to about 329 MJ or 91 KWh of energy. That's equivalent to 2.55 gallons of gasoline, so about 39 mpg. The world record for Teslas using hypermiling techniques and a similar amount of energy is about 700 miles, so it's close to an order of magnitude better for electric cars. With multiple passengers in the car the energy efficiency per passenger increases. Trains are also quite efficient on a per passenger basis, with the ability to carry a passenger about 2000 miles for the same amount of energy as a horse traveling 100 miles. Aircraft can go about 80 mpg per passenger, so they are about 2x as efficient as a horse.