The good news — New vehicle CO2 emissions and fuel economy have improved significantly over the past 50 years. In fact, cars have become twice as powerful and fuel efficient—proving that progress isn’t a trade-off. The charts below are interactive so be sure to hover over data points to reveal specific values for each year.
Since 1975, vehicle miles per gallon in the United States has improved from 13.1 mpg to 27.1 mpg in 2023.
Manufacturers are applying a wide array of electrification technologies.
Innovation in the automobile industry has led to a wide array of technologies available to manufacturers to achieve CO2 emissions, fuel economy, and performance goals. Figure
ES-2 illustrates manufacturer-specific model year 2023 usage rates for technologies that represent increasing levels of vehicle electrification, as well as the recent adoption trends of those technologies across the industry. The technologies in Figure ES-2 are utilized by manufacturers, in part, to reduce CO2 emissions and increase fuel economy. It is also clear that manufacturers’ strategies to develop and adopt these technologies are unique and vary significantly. Each manufacturer is choosing technologies that best meet the design requirements of their vehicles.
Vehicles that have stop/start systems generally use a larger alternator and enhanced battery, which enables the vehicle to turn off the engine at idle to save fuel. Hybrid vehicles use a battery to recapture braking energy and provide power when necessary, allowing for a smaller, more efficiently operated engine. Hybrids can be separated into smaller “mild” hybrid systems (MHEVs) that provide launch assist but cannot propel the vehicle on their own, and “strong” hybrid systems (HEVs) that can temporarily power the vehicle without engaging the engine. Plug-in hybrid vehicles (PHEV) have both a gasoline engine and a battery that can be charged from an external electricity source, and generally operate on electricity until the battery is depleted or cannot meet driving needs. Full battery electric vehicles (BEVs) employ a battery pack that is externally charged and an electric motor ex- clusively for propulsion, and do not have an onboard gasoline engine.
In model year 2023, gasoline vehicles with stop/start, mild hybrids, strong hybrids, PHEVs, and BEVs all gained market share and captured their largest market shares on record. The technologies shown in Figure ES-2, along with many others, continue to evolve and impact many aspects of the industry. This trend will likely continue as production of mild hybrids, strong hybrids, PHEVs, and BEVs are expected to grow across the industry in coming years.
In model year 2023, compared to model year 2022, the four largest vehicle types continued their trends of reduced CO2 emissions and increased fuel economy. Minivan/vans, which accounted for less than 3% of new vehicle production in model year 2023, had CO2 emissions that were unchanged. Most notable is the 60 g/mi, or 24%, reduction in the average new vehicle real-world CO2 emissions within car SUVs. This improvement in CO2 emissions stems from the influx of BEVs within car SUVs, with BEVs now accounting for 36% of all MY 2023 car SUVs. The car SUV vehicle type now has the lowest average new vehicle CO2 emissions.
Since 1975, the market has shifted dramatically away from sedan/wagons and towards truck SUVs and car SUVs. Until recently, the sedan/wagon was the most efficient vehicle type, so the market shifts toward other vehicle types with lower fuel economy and higher CO2 emissions offset some of the fleetwide benefits that otherwise would have been achieved from the improvements within each vehicle type. However, the growth of electric vehicles, particularly within the car SUV vehicle type, is changing the relationship between vehicle types and overall average new vehicle real-world CO2 emissions.
Average new vehicle fuel economy, horsepower, weight, and footprint are all increasing.
Overall vehicle trends are influenced both by vehicle technology, and by the changes in the distribution of vehicles being produced. For gasoline (and diesel) vehicles, increased weight,
size, or horsepower is likely to result in higher CO2 emissions and lower fuel economy, all else being equal. For BEVs, increased weight, size, or horsepower will impact the vehicle’s efficiency (as measured in kilowatt hours per 100 miles or miles per gallon of gasoline equivalent), however BEVs produce zero tailpipe emissions regardless of their weight, size, or horsepower. The growth of BEV production could also impact the fleet’s overall fuel economy, horsepower, and weight trends, as BEVs are on average more efficient, more powerful, and heavier than comparable vehicles.
Over the history of this report, there have been three distinct phases, as shown in Figure ES-4. Between 1975 and the early 1980s, average new vehicle fuel economy increased rapidly, while the vehicle weight and horsepower fell. For the next twenty years, average new vehicle weight and horsepower steadily increased, while fuel economy steadily decreased.
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