"It's true that things will probably never be the same again," said the Mercedes-Benz executive. "But it is really quite similar to what happened after the first bomb attacks on airports.

"Airports have never been the same, but people got used to it."

The executive was talking about the effects of the recent wave of terrorist murders and kidnappings that has stunned West Germany and produced something of a siege mentality among government and business elite who are the targets of such attacks.

"A few years ago, you could walk routinely through a company's headquarters, but today nobody argues with a guard whom they now take for granted," the executive continued.

"Certainly it is depressing and affects our spirit. But it is definitely not depressing in a paralyzing way. Life has got to go on."

An exeuctive of the huge Ford Motor Co. plant in Colgone pointed to this week's Frankfurt auto show, the world's largest, as an example of how West Germany "must not be paralyzed." In the midst of the anxiety about terrorism, hundreds of top West German automobile executives, along with a million other visitors, turned up for the event.

For the most part, the precautions being taken by the captains of West German industry and their families are hidden from view.

The big Deutsche Bank is installing bulletproof windows and television cameras in homes of top officals. Many firms are adding bullet-proofing to corporate cars and hiring private bodyguards at $25 an hour to augment already beefed-up company security forces.

A meeting of top Ford Executives from around the world was moved from Cologne to London. At the plant, executives are taking different routes to work each day and going in different doors.

A private company in Frankfurt that teaches the use of handguns reports some 60 corporate applicants in recent weeks, although police advise that nothing less than a sub-machine gun outlawed in West Germany - is likely to be helpful against heavily armed terrorists.

Frankfurt police, in fact, are worried about "a James Bond mentality" getting out of hand among civilians seeking exotic devices to protect themselves.

The siege mentality that has gripped the nation's leaders and the police, who are trying - without much success thus far - to crack the terrorist wave, is much more visible.

The situation, while grim also, seems to have a certain "Keystone Cops" quality about it as the daily signs of overpowering police presence and crime-fighting technology seem to be growing in proportion to the frustration of not being able to find the terrorists.

The immediate problem is to catch the abductors of industrialist Hanns-Martin Schleyer, who was kidnapped from a two-car convoy on a Cologne street 15 days ago by an efficient band of leftist anarchists. Three security guards and a driver were killed in the ambush attack. The kidnappers are demanding the release of 11 jailed terrorists in exchange for Schleyer's life.

The police are also still looking for the extremists who killed banker Juergen Ponto July 30. It was only by luck, when a woman in a small border town thought somebody looked like a terrorist, that police were able to capture two persons wanted in the machine-gun death of federal prosecutor Siegfried Buback in April.

Armored cars resembling miniature tanks that normally patrol casually through this city are now here in large numbers surrounding key ministries and homes of leading politicans. The Justice Ministry, for example, is ringed by armored cars, barbed wire and sand-bagged sentry posts. It looks something like the U.S. Embassy in Saigon during the height of the Indochina war.

Even the U.S. Embassy is rapidly putting up a thick metal fence, as other diplomatic missions take similar precautions.

Police with sub-machine guns and dogs are now clearly evident on otherwise quiet streets in government and diplomatic quarters. Special anti-terrorist commando forces in black berets can be seen whisking through the city in unmarked sedans. Computers here and at the headquarters of the federal criminal office in Wiesbaden spin out reams of information on terrorist suspects.

Nevertheless, the small but determined band of terrorists, seemingly bent on destroying West German society, continues to elude police.

Indeed, despite its impressive array of technology and manpower, the Schleyer case in particular has turned up serious and sometimes embarrassing holes in West German security.

While the streets of major cities are loaded with police these days, seven banks in Cologne - the city where Schleyer was abducted - have been successfully held up since his kidnaping.

Some of those funds could be going to terrorists, who operate in a sophisticated style with expensive weapons, cars, hideaways and false documents.

The Schleyer case dramatized the long-known but uncorrected fact that computerized crime information plans in many West Germany's 10 federal states are not compatible. The result is that federal manhunts and quick police responses in the first moments of an incident are sometimes hindered.

While police were setting up roadblocks right after the Schleyer attack, for example, the West German road travel service's helicopters were telling motorists which roads to use to avoid the congestion.

The criminal office found out about the Ponto killing on television news.

German orderliness may also be getting in the way. A good Samaritan citizen trying to follow the Ponto getaway car stopped at a red light, while the terrorists went through it.

The sudden demand for protection may also have thrust many relatively inexperienced policemen into emergency situations. State officials went to great lengths this week to pull bullets out of walls to prove that the police with Schleyer managed to get off at least 11 shots while the kidnapers pumped more than 300 shots at them.

Most important, however, is that the police apparently have not been able to penetrate the band of hard-core terrorists.

Unlike situations in Northern Ireland or in the Middle East, where large numbers of people are involved and there are strong ideological forces and indiscriminate violence, police in this country of 61 million are faced with a tiny handful of people who are very selective in their targeting and who recruit no one for their gangs except people they know.

Even then, some gang members probably have only a vague idea of what is going on and only a few have full access to actual attack plans.

Unlike a lot of other Western countries, West Germany has relatively little crime, so the attack on highly visible pillars of the prosperous post-war society can cause considerable public uneasiness.

What to do about it is another question. Chancellor Helmut Schmidt has taken what may be the only interim choice at this point in calling on the public to help in the hunt, particularly fringe sympathizers who frequently have at least bits of information that seem to escape the police.

Over the long run, however, Bonn will have to confront such problems as what to do about some lawyers, with apparent extremist sympathies, who are widely believed to have helped mastermind terrorist plots, including providing links between jailed terrorists and colleagues on the outside.

Banks will have to be more careful, car license plates made less easy to switch and guns less accessible, security experts say, to hinder the flow of terrorist logistics.

Ultimately, the experts believe a new style of police operations will have to be developed.