According to McDonald's nutrition facts a \($M\) provides \($C\) kiloCalories of energy. (1 dietitian's calorie is 1000 physicist's calories.) A typical automobile lead-acid battery can supply 50 Ampere-hours at 12 Volts. We can compare these by converting the energy specifications to common units. The SI unit of energy is the Joule=1 Watt-second. One physicist's calorie is 4.2 Joules.
How many Joules are there in a \($M\)?
How many Joules are there in a car battery?
Which tastes better? :-)