During his campaign for county executive last fall, Republican Lawrence J. Hogan frequently accused incumbent Democrat Winfield M. Kelly Jr. of wasting county money.

One of Hogan's targets was Kelly's county-owned car, a black 1975 Ford LTD. If elected, Hogan promised, he would never drive such an ostentatious car. An old station wagon would be good enough for him.

Now county executive, Hogan has kept his promise. Each morning he drives an old station wagon to the County Office Building in Upper Marlboro.

But Kelly's car, affectionately called "Big Black" by members of his staff, is being used by a Hogan -- Lawrence J. Hogan Jr. -- the executive's 22-year-old son who is also one of his assistants, assigned various liaison and troubleshooting tasks.

"After Winnie lost, I had thought Larry was going to sell Big Black," County Council member Gerard T. McDonough said yesterday. "But then I kept seeing it in the [county] garage. It's easy to recognize because it has so many antennas [for a telephone and police radio], that it looks like a Russian trawler. Finally I heard Larry Jr. was driving it."

Larry Hogan Jr. says he drives the car only when on county business and does not take it home at night. But the car was reportedly seen outside his apartment on a recent weekend.

"Sometimes when I go to a speaking engagement from work I stop at home to change clothes," the younger Hogan said. "That's why the car might have been seen there."

Hogan spokeswoman Barbara Coleman pointed out that the car has 137,000 miles on it and added that another Hogan aide, Jack McHale, uses it sometimes.

Hogan Jr. said yesterday he began using the car when his own gasoline bills soared to $150 a month. "It's only right that I should use a county car when I'm out on county business," he said, "especially on my salary."

The younger Hogan's salary has also been a topic of debate recently. When Hogan Sr. announced his son's appointment in December he said he would be paid $11,000 a year -- less than half the normal salary for top assistants to the executive.

But Hogan Jr. is being paid $14,000 a year because the County Council would have had to pass special legislation to pay him only $11,000 and Hogan Sr. did not want to set a precedent by asking the council to change salaries.

"I could probably make more money working somewhere else," the younger Hogan said yesterday. "But I'll take whatever they want to pay me."

At least one council member, McDonough, said he thought the younger Hogan is underpaid. "I know I wouldn't take that job for $14,000 a year," he said.

As for the car, Hogan Jr. said he had been thinking of proposing that the county buy smaller cars.