The head of the Environmental Protection Agency has selected for her own government car one of the biggest polluters on the road--a four-door 1982 Oldsmobile Ninety-Eight Regency Brougham with a diesel engine.

What's more, the EPA is leasing the car for the administrator, Anne M. Gorsuch, at a yearly rate of $7,364--more than four times the auto leasing fee paid by Gorsuch's predecessor, Douglas Costle.

The dark gray car, specially ordered for Gorsuch by Pohanka Auto Leasing earlier this year, has matching slate gray leather bucket seats, a vinyl top, AM-FM stereo, a telephone, power windows and locks, air conditioning, wire wheels and, according to an EPA employe, "fancy hubcab covers."

Why so fancy? One government official explained that cars for government heads should be "an extension of their office" because a lot of work is done in the car.

EPA's new luxury car replaces the smaller and plainer gasoline-powered midsize family car, the Mercury Zephyr, that Costle used for an annual cost of $1,800 a year.

The Oldsmobile "meets the General Services Administration mileage requirements and all the current pollution standards of the U. S.," an EPA spokesman said when asked about the car.

Nonetheless, environmentalists have criticized the choice of such a car by the EPA head, charging that, even though it may meet federal pollution standards, it emits more pollution than most cars on the road, including other diesel cars.

The bigger and heavier the car, the greater the particulate emissions, which makes the luxurious and heavy diesel-powered Oldsmobile one of the largest polluters.

However, according to Herbert Johnson, a transportation operations specialist at GSA, the Oldsmobile diesel is the only big car that meets the auto-mileage standards required by the GSA--24 miles a gallon.