For example, a study by the University of Michigan Transportation Research Institute states the energy intensity of car transportation is on average 57% higher than air transports. In other words, a car emits more CO2 than the average planes because they consume more energy to transport the same amount of passengers.

The comparison of CO2 emissions between planes and cars depends entirely on the distance of the trip and the number of passengers in the vehicle. For long-distance travel (over 500 miles), a modern, fuel-efficient commercial aircraft often emits less CO2 per passenger mile than a solo driver in a standard gasoline car. This is because planes are optimized for high-altitude cruise efficiency, and the carbon footprint is shared among hundreds of passengers. However, for short-haul trips where a car is occupied by three or more people, the car is almost always the "greener" choice; short flights use a disproportionate amount of fuel during takeoff and landing. In 2026, the data shows that an average car trip (with 1.2 passengers) emits about 171g of CO2 per kilometer, while a domestic flight emits about 246g per kilometer per passenger. However, if you are comparing a solo drive to a flight, the plane is often more efficient on a per-seat basis. To truly minimize your footprint, electric cars and high-speed rail remain significantly cleaner than both traditional cars and aviation, with trains often emitting 80-90% less CO2 than a flight over the same distance.