Washington, D.C. – Vehicle registrations are up 3.5 percent in the metropolitan Washington area since 2005, according to a presentation given today to the National Capital Region Transportation Planning Board (TPB). Maryland and Virginia area jurisdictions saw increases in registrations of three percent and 5.6 percent, respectively, whereas registrations decreased by 5.8 percent in the District of Columbia during that same period.

Due to the fact that an area’s emissions are very sensitive to the composition of its vehicle fleet, the TPB periodically conducts a regional vehicle inventory as part of its air quality conformity requirements. Beginning in 2005, a vehicle identification number (VIN) decoder has been applied to vehicle registration data for use by the TPB to examine the composition of the vehicle fleet in the region every three years.

Mobile source emissions vary significantly according to vehicle characteristics, including vehicle type, fuel use, and year of manufacture. Wednesday’s presentation – which was based on data as of July 1, 2008 that includes essentially every vehicle in the region – provided a breakdown of these characteristics. Since 2005, the region’s vehicle fleet has changed significantly, creating a number of policy implications.

Prior to 2004, the percentage of passenger cars relative to sport utility vehicles (SUVs) had been steadily declining for each model year, resulting in an almost equal share of new vehicle purchases. However, the trend reversed in 2004, and this reversal has continued progressively, with passenger cars now claiming 60 percent of new purchases to 40 percent for SUVs.

Within their “type,” newer vehicles tend to have lower emissions relative to their older counterparts. The TPB’s presentation indicated that the region’s fleet has gotten older since 2005, and the increase in vehicle age is even greater for light trucks, SUVs, and heavy trucks than for passenger cars. Mobile source emissions will increase as a result of fewer new vehicles being purchased. Although the number of hybrids has increased more than threefold, they still only constitute less than 1.5 percent of the entire region’s fleet, and are not currently significant enough to offset the increased emissions of older vehicles.

Based upon these factors, Ron Kirby, Director of Transportation Planning at the Metropolitan Washington Council of Governments (COG), told the Board that the department will be re-estimating emissions forecasts for its current air quality conformity assessment.

To reinforce the shift from SUVs to smaller passenger cars, and to encourage purchases of newer vehicles, concepts such as ‘Cash for Clunkers’ are currently being considered by Congress. These proposals would provide vouchers worth up to $4,500 toward the purchase of a new vehicle upon turning in an older one, with specific standards placed on the fuel efficiency of both the trade-in and the new vehicle.

Harriet Tregoning, TPB member and Director of the D.C. Office of Planning, noted that despite an increase in population and household income, the District had seen a significant reduction in the number of vehicle registrations since 2005, indicating that people are choosing a less car-dependent lifestyle. Tregoning suggested that any Cash for Clunkers proposal need not require that vouchers be spent on purchasing new vehicles.

The data sources for the report include vehicle registration data as of July 1, 2008 from the District of Columbia Department of Motor Vehicles, Maryland Motor Vehicle Administration, and Virginia Department of Motor Vehicles.