Clad in white doctor's garb and flanked by his Igor-like assistants El and Mo, a crazed Dr. Isuzustein screams for more power.

An Isuzu pickup and Impulse car rise on hydraulic platforms and in a blaze of special effects a shining red Amigo bursts forth. In the next few seconds, the nefarious Joe Isuzu, a.k.a. Dr. Isuzustein, zooms off as his awestruck sidekicks scream: "You've created a monster!"That monster is American Isuzu Motors' latest offering, and Isuzu is banking on another outlandish performance by the lying scoundrel to make the Amigo its most popular vehicle.

Joe Isuzu is really David Leisure, a once-starving actor discovered in an 80-person casting call by Della Femina McNamee, WCRS, the Los Angeles advertising agency that masterminded Isuzu's campaign.

"We picked David because he really epitomized the sleazy car salesman we wanted," said Dennis Remsing, Della's senior vice president and managing director. "He really looked the part."

The ads have made Leisure a television success, catapulting him into a role as the contemptible neighbor in NBC's new situation comedy "Empty Nest."

It's also been a big boost for the company.

But there is some concern that the viewers are concentrating too much on Joe and missing the cars in the commercials. Consequently, Joe's prominence in the commercials is being lessened.

"In the past year, we've been trying to change the ads to give more information about the product," Remsing said. "Joe used to stand in front of the trucks and talk about them. Now he's driving them more and you'll hear him scream out more features on the vehicles that we've never done in the past."