If there's a recession coming, you'd never know it by looking at the rental car industry.

Some of the industry's biggest companies report results ranging from mixed demand to continuing growth, especially in vacation reservations, into 1991. And, while they are keeping a weather eye on the economy and are ready to react to any adverse effects of a recession, they are far from pushing any fiscal panic button."For Budget, we expect continued growth," said Budget CEO Clif Haley. "For the travel industry, some rocky times."

"If we just keep going the way we're going, we'll be doing great," said Avis Vice President Jim Collins. "We're up 8 to 10 percent" this year over last.

And Hertz Chairman and CEO Frank Olson said his company is seeing both some soft areas and some high points.

All said they see better results in leisure travel than in business travel. And all pointed to service improvements as a key to success in the car rental industry.

"I think the best way to put (a 1991 forecast) in perspective is to look at this year's results," said Budget's Haley.

For the first 11 months of 1990, he said, the number of people flying domestically was up only 1.6 percent. Budget's transactions were up 15.5 percent, making the company "the only one of the majors that has gained market share ... about $130 million of increased revenue for the year in the United States," Haley said.

Haley said 1990 figures show improvement especially in leisure travel. That segment of the business, he said, is up "much more dramatically than the business side." And, he said, the trend has continued despite predictions during the second half of 1990 of an economic downturn.

"We don't share the traditional view of many of the economists about all portions of the service sector. Our perspective is that, as it relates to travel, a number of changing forces dictate leisure travel is going to continue to be a pretty good buy," he said.

He said continuing discounts in air fares, overbuilding in the hotel and cruise ship industries and more two-income families with more discretionary income all combine to stimulate travel even in an uncertain economy.

"And there are changed demographics: more people, more short travel. All this has resulted in more and more people traveling. Even within the service sector, the travel piece is growing so rapidly, it's outpacing what's happening in the economy overall," Haley said.

For example, he said, Budget's advance reservations for Florida through January are up 40 to 45 percent.

Avis' Collins said the overall outlook for 1991, "I have to believe, will depend on what President Bush does in January in the Persian Gulf. That's going to be a bellwether. I'd anticipate that if something definitive doesn't come out of what they do there, we probably are going to feel it" in negative results.

Collins said he sees "a little softening in some markets. But coast-to-coast, we're not hurting."

Olson said Hertz has seen "some softening in business travel as a direct result of the economy.

Olson said about 65 to 70 percent of Hertz' business is tied to air travel and warned the outlook for the new year will depend in large measure on what happens to air fares.