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More people in the vehicle means less fuel use per person: Comparing SUVs and cars

by Michael Sivak.

Compared with cars, SUVs consume more energy per vehicle mile. Consequently, SUVs emit more carbon dioxide per vehicle mile than do cars. However, in the United States, the typical occupancy is higher for SUVs than for cars. The issue of interest in this study was the resultant energy usage per occupant distance. In other words, does the higher occupancy of SUVs compensate for their higher energy consumption per vehicle distance when considering energy consumption per occupant distance?

The analysis used the following data for cars and for SUVs:

The results are shown in the table below.

Sivak occupancy

The final step of the analysis (with the results shown in the last row of the table above) took into account the fact that the increased occupant weight being carried by SUVs results in slightly lower fuel economy. The Environmental Protection Agency estimates that an extra 100 pounds in a vehicle can reduce fuel economy by about 1%. Given that the difference in the average occupancy between SUVs and cars is 0.29 persons, and assuming the weight of 100 pounds for an average occupant (including men, women, and children), the calculations were rerun assuming a reduction of the average fuel economy of SUVs by 0.29% (from 23.3 mpg to 23.2 mpg).

In conclusion:

  • For model year 2017 vehicles, the average fuel consumption per vehicle distance is about 30% higher for SUVs than for cars. For example, the average SUV consumes 42.9 gallons of fuel per 1,000 vehicle miles, compared with 33.1 gallons for the average car.

  • However, taking into account the increased occupancy of SUVs, as well as the increased occupant weight, results in the average fuel consumption per occupant distance for SUVs being only about 10% higher than for cars. For example, the average SUV consumes 23.6 gallons of fuel per 1,000 occupant miles, compared with 21.5 gallons for the average car.


Michael Sivak is the managing director of Sivak Applied Research and the former director of Sustainable Worldwide Transportation at the University of Michigan.


Comments

Peter_XX

So, should we promote SUVs then?

HarveyD

The truth is that SUVs consume and pollute 15% more than the average car. Large pick-ups probably consume and pollute another 15% more.

Since those two types of vehicles are currently the best sellers in USA and part of Canada, it seems evident that we will not reduce pollution and GHGs for years.

Hope that our children and grand-children will be wiser?

mahonj

You can easily fit 4 people in a saloon car.
If these people were not using SUVs, they could easily transport the people in a saloon.
So I do not buy the notion that SUVs are not as bad as they might be due to higher occupancy.

SJC

Some people drive a 12 mph 6000 pound SUV to the store with one person to buy a bag of groceries. Americans have been and continue to be very wasteful.

Lad

The major reason U.S. drivers buy huge SUVs is that's what the dealers try to sell...ICE SUVs with high margins.

Money drives almost everything in a capitalist society where the welfare of the people, hardly moves the priority needle.

SJC

People convince themselves that they need a big SUV to tow a boat one weekend a year. Americans are indoctrinated to be consumers.

Christos Dimou

The analysis is quite useful but still we have to consider that the average occupancy is quite low since driving is predominately a private form of transportation.

The SUV craze is not going to go away any time soon. So it is imperative for the auto industry to focus on optimizing their power-trains to increase real fuel efficiency.

Engineer-Poet

Time for a 1-gallon fuel consumption limit on the first 50 miles of travel on the standard driving cycle, starting with a fully-charged traction battery.

SJC

Fourty+ years after the oil embargoes and they are still selling big SUVs.

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