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11-000612 M.Edie (Part 523)

Mark D. Edie

Office of the General Counsel

Ford Motor Company

1350 I Street N.W., Suite 450

Washington, D.C. 20005

Re: Request for Interpretation of 49 CFR 523.2 AND 523.5(b)(2)

Dear Mr. Edie:

This is a response to your letter on January 21, 2011, in which you requested an interpretation of 49 CFR 523.2 and 523.5(b)(2) as they would apply to the classification of a motor vehicle with components affixed to its undercarriage. The specific components described in your letter are tire aero deflectors, which are attached in front of the tires in order to reduce aerodynamic drag and thereby improve fuel economy. Your letter states that in order to perform as needed, some of the components may be between 20 and 15 centimeters from their lowest point to the ground. The components are made of flexible plastic and capable of bending without breaking and returning to their original position after encountering solid objects up to 20 centimeters in height at typical off-road speeds. You requested our confirmation that this type of component would be excluded from the running clearance measurement in 49 CFR 523.5(b)(2), and thus allow vehicles equipped with these components to be classified as light trucks for CAFE compliance purposes, provided that they meet all other required criteria for that classification. This letter provides the agencys opinion based on the information provided.

By way of background, the National Highway Traffic Safety Administration (NHTSA) does not endorse or approve the classification of any motor vehicle. This is the responsibility of the vehicle manufacturer, who must also ensure that the vehicle complies with all applicable regulatory requirements. In order to comply with CAFE requirements, the manufacturer must classify its vehicles according to the definitions in 49 CFR Part 523, as promulgated under 49 U.S.C. 32901(a)(17)-(19). Improper classification can result in NHTSA determining that a manufacturers CAFE compliance obligations for its passenger car and light truck fleets are different from those assumed by the manufacturer, and create difficulties in meeting the standards.

NHTSAs regulations at 49 CFR 523.5 provide two basic ways in which a vehicle can be classified as a light truck for CAFE purposes: 523.5(a) covers vehicles that the agency considers functional light trucks, that are not passenger cars because they were not manufactured primarily for transporting up to ten individuals; and 523.5(b) covers vehicles which are expressly excluded from the passenger car category due to their capability for off-highway operation.[1] Your question focuses on 523.5(b), which states that a vehicle must either:

(1)(i) [Have] 4-wheel drive; or

(ii) [Be] rated at more than 6,000 pounds gross vehicle weight; and

(2) [Have] at least four of the following characteristics calculated when the automobile is at curb weight, on a level surface, with the front wheels parallel to the automobile's longitudinal centerline, and the tires inflated to the manufacturer's recommended pressure

(i) Approach angle of not less than 28 degrees.

(ii) Breakover angle of not less than 14 degrees.

(iii) Departure angle of not less than 20 degrees.

(iv) Running clearance of not less than 20 centimeters.

(v) Front and rear axle clearances of not less than 18 centimeters each.

Running clearance is defined in 49 CFR 523.2 as the distance from the surface on which an automobile is standing to the lowest point on the automobile, excluding unsprung weight.

We have previously interpreted 49 CFR 523.5(b) to mean that it does not require a vehicle to meet four of the five criteria [of 523.5(b)(2)] at all ride heights; however, a vehicle must meet four out of the five criteria in at least one ride height.[2]

In the situation presented in that prior interpretation, the vehicle was equipped with a driver-controllable variable ride height suspension system. In some positions, the vehicle would have had a running clearance of less than 20 centimeters, but the agency determined that it was appropriate, for CAFE classification purposes, to measure the vehicles running clearance with its adjustable suspension placed in the position(s) intended for off-road operation under real-world conditions.[3]