When Charles Vann graduated from high school, his grandparents said to him, "Pick out a car and we will buy it for you." Vann, who is 18,, now drives a $17,500, 18-foot long Cadillac Fleetwood Brougham d'Elegance with dark blue florentine velour sofa seats and a blue tint sun roof. His friends say, "Well, right on Vann." Why not?

As Vann cruises through the city caressed by blue shades and stereo, the Cadillac mystique that for the past 75 years has enchanted a loyal following begins to unfold. Vann's "main man" and "riding buddy," Benjamin Suter, 17, has tilted back into one of six seating positions apparently gazing through the soft ray glass roof top. Vann has settled back into a confortable, elbow-supported lean to his right, a posture he says is more pronounced when his girl friends is riding with him.

"When I first hopped in it, it was really outta sight," Vann said, "I had never been in anything like that before. People started staring at you and I was just getting all kinds of attention.People were saying, 'oh, wow, who is he?" All of the girls just went off. The cops stopped me about a dozen times. They said I was looking good, but real suspicious, you know."

That is the Cadillac mystique - over two tons of steel, chrome and fancy trim crafted into a sleek, stylized version of an airplane that cannot fly, but can do practically everything else.

"We appeal to people who want the best," said K. R. Wolfe, the Washington area's Cadillac Motor Car Division zone manager. "We've noticed that when we have fuel problems or the economy is not doing well, people become very quality conscious - not price conscious."

He said Cadillac sales were never seriously affected by the fuel crisis and sales are up 12 per cent nation-wide this year over last and 40 per cent this year in the Washington area. He said a lot of the increase is due in part to the popularity of Cadillac's new small-sized Seville. The Seville, which is 25 inches shorter than most American luxury cars, is unique in that it comes in 14 different colors with the fancy accent paint striping.

Ironically, it has been black customers - who less than 20 years ago years ago were excluded as targets of Cadillac advertisements - who have done much to perpetuate the cars mystique, as well as influence its esthetic evolution.

"We came to recognize," said Jere kitzmiller, formerly with GM's Detroit Cadillac Division, "that blacks are very style conscious, that they were the trend-setters in clothes and automobiles."

When black Cadillac salesmen began arguing that they could sell more cars if they came in more colors, Cadillacs became available in such colors as Dreamy Cream and Frost Orange Firemist and virtually every other frosty fire mist imaginable.

"At one time we couldn't buy homes on 16th Street but wehad the money," said diehard Cadillac owner, Petey Green, a popular radio talk show personality. "We had to do something to get some status and since all hte big shot white people had Cadillacs we started buying em too."

Said Clarence Williams, a salesman for Coleman Cadillac, "When I was growing up in Washington, shooting marbles when I was 10, the fellows used to stop the game when a Cadillac rolled past. We would say one day I'm going to have one of those cars."

Williams, who has won every major Cadillac selling award and has sold over $1 million in Cadillacs a year for the past six years, said "as far as ethnics go, Jewish people buy most Cadillacs. You also have a lot of Arabs coming in to buy fleets of car and the only place they have to drive them is around the deserts."

Cadillac began its ascendancy just after World War II, where it had been used personnel. Before then, packards led the field, Wolfe said.

"Yeah," says Green. "I remember the preachers in this town (Washington). They used to drive packards until Cadillac came out with the fishtail. All of them started buying Cadillacs . . . you know, a preacher got to say a step ahead of the congregation, right? Then, all the funeral home directors started getting Cadillacs because all the preachers had them."

Says Wolfe, "We invented the fin, not the fish. That's Chrysler."

Cadillac dealers are reluctant to talk publicly about the one type of client who has probably done more than any other to keep their product in the limelight - the underworld figure, frequently the pimp.

"It is a good reflection upon our car," says Kitzmiller, "that although pimp types do buy our product, that has not discouraged respectable buyers."

Cadillac salesmen, who seem to enjoy a lawyer-client type of relationship with many of their "questionable" buyers, requests anonimity when discussing them.

"This one fellow comes in with a envelop packed with $1,000 bills and says show him something," said a local Cadillac salesman during a telephone interview. "Hey, I show him."

This salesman says he knew of another, now out of business Cadillac dealer, who used to sell to nothing but drug dealers and bank robbers. "He knew he would get the money or the car," the saleman said. "If they got caught, he repossessed the car, if they got away - he got some of the money."

Of late, many salesmen agree, financing a Cadillac has been simplified and now almost anyone making around $15,000 a year can buy one.

Cadillacs can be had from about $13,000 to $25,000 (for the limousine). Unlike most luxury cars, however, many Cadillac salesmen are willing to extend payments beyond the traditional two-and three-year period.

In fact, some salesmen encourage the development of "loyal" customers. They can buy a Cadillac one year and trade it in the next.

"They end up paying for the cars for damn near a lifetime," one salesman said, "but it's not a bad deal especially if they really want the car."

According to Green, the image of blacks and their Cadillacs have had some negative effects, particularly in Washington - and some residents still must do some soul searching before going out to buy one.

"I remember when the congressmen on the Hill used to debate what was going to be done about the poor people in this city," Green says, "but the people on Capitol Hill only had to look out of their office buildings windows right into some of these alleys and see all of them Cadillacs parked out there.

"Some would say why do you people need assistance when you got all them Cadillacs. It didn't make any difference that they had to park their cars next to outdoor toilets. The congressmen only saw the cars."

"When I was in the joint (jail)," said Green, "that's all the young criminals I get out, the first thing I'm gonna get is a diamond ring, a watch, some clothes and a Cadillac."

Earnest Wright, a 32-year-old construction worker has never been in jail, but he can understand how Green's young criminals must have felt. "Like man, I used to come home all sweaty and tried and mad and I'd try to get something to eat, then get a little nip and watch TV and hit the sack. Like that was it."

Wright sais he nothing to show for his efforts but a headache and abackache the next day - until he decided to defy his name-calling friends (they would sneer and call him a bourgeois) and get himself a Cadillac Coupe de Ville. Like Vann, Wright says the women notice him more, so coming home from work will never be quite the same for him.

"I deserved a Cadillac," said Wright. "I figured it had to be the best nothing except this car. Yeah, it's more than a ride because if that's all I neede I would have bought a Honda."

"When it comes to automobiles," Wolfe said, "that is the second largest purchase you will make next to a home. It's all part of the kind of image a person has of himself. People want something different."

Timothy Servo, a 40-year-old self-employed businessman drives a 1977 Damson Plum Firemist El Dorado, with opera windows lamps and the classic "El D" script on the side panel, and tuxedo grain vinyl padded roof, with red florentine d'elegance interior.

"I have to drive a lot so I might as well enjoy it. To enhance that he has installed a $300 stereo cassete tape system and a television. He is planning to put in a bar and a telephone."

"This is a good investment for $35,000," Servo said. "I can tell this car in 10 years and still get more than I paid for it."

Says Vann, "It's just the beauty of the car and the way it rides. I used to have a (Buick Electra) 225 before I got this and now I don't even want to ride it anymore.

"When the weather was bad and all I made so many new friends that it loose all the people I met after I got the car and just bang out with the ones who knew me before I got it.

"I mean, its something else. But next time, I think I'll try a Seville."