Any time is new-model time, as auto industry continues its roll

Gone is the hoopla of the pre-energy-crisis world of the 1950s, '60s, and early '70s. Gone also are the paper-covered windows of the dealerships and the eager anticipation of the motorists for a peek at ''tomorrow's cars.''

New-model time in the mid-1980s is a misnomer. Because of the rapid pace of technology and the cost of developing a new car line, automakers don't wait for an arbitrary date on the calendar for showing off their new cars. They now introduce a car whenever it's ready.

GM, for example, had an early ''launch'' for its top-line, 1985-model luxury cars which arrived in the showroom last spring. Ford unveiled the Tempo/Topaz in June last year. You'll have to wait, however, to take the wheel of the new Ford Aerostar, the carmaker's downsized van.

Here's a rundown, starting today with General Motors, of what's new and not so new as the resurgent US auto industry continues its roll: General Motors

Highlighting the impact of the imports on Detroit, GM's biggest car division, Chevrolet, is selling two new Japanese imports for 1985, one on the West Coast, the other on the East Coast.

The 1-liter, 3-cylinder, Suzuki-made Sprint, on sale only in 9 Western states , is testing the American market for mini-sized, mini-powered vehicles and comes only as a 3-door hatchback. The larger Spectrum, built by Isuzu with a 1.5-liter , 4-cylinder engine, comes as both a hatchback and 4-door notchback and will be sold in 16 Eastern states.

Introduction of the Chevrolet rear-drive minivan, featuring a 2.5-liter engine as base power, plus a zippy 4.3-liter V-6 as an option, has been delayed till late November or beyond. The rear-drive Astro, plus Ford's upcoming Aerostar, will vie with Chrysler's ''miracle van,'' the Dodge Caravan and Plymouth Voyager, which hit the road a year ago and found ''instant gold.''

The factory wheels for the controversial GM-Toyota joint-venture car, based on the front-drive Toyota Sprinter, are due to turn by the end of the year. The car should hit the highway in spring, either as a late-'85 vehicle or perhaps the first of the '86 models.

The Caprice/Impala and Monte Carlo are essentially unchanged with the 4.3 -liter V-6 as the new base engine. The spirited Monte Carlo SS, street version of a racecar, still uses the 190-horsepower V-8 for power. Performance and handling are superb.

The Chevrolet version of the long-harried GM X-car, the Citation, is around for at least another year, although the 2-door notchback coupe is gone. Today's Citation II is a far better car than the earliest models which are still bound up in litigation.

Chevrolet has tried to soften the suspension of the sporty Corvette without sacrificing its ability to stick to the road. Tuned port injection pulls more power out of the 5.7-liter V-8. Camaro launches a race-ready IROC (International Race of Champions) Z28 for the performance buff. Both the Camaro Berlinetta and Sport Coupe have a new nose and optional 2.8-liter V-6 engine.

A popular econocar, Chevette moves into yet another model year in about the same form as when it first hit the blacktop in the mid-1970s.

Buick is breaking new ground in electronics, both in highly sophisticated engine controls as well as dashboard displays on its big cars.

Like Chevrolet, Buick has dropped its 2-door notchback X-coupe, but hangs on to the 4-door Skylark for at least another year. Standard engine in the the sporty T-type is the port-injected 145-h.p., 2.8-liter V-6.

The front-drive Regal Somerset, Buick's version of GM's N-body car, is offered in the traditional Buick mold and is aimed at the driver who wants a more conservative vehicle without the exaggerated flare of some competition. A choice of 4-cylinder or 3-liter, V-6 power is offered.

The standard Regal T-type has a new grille as well as performance-type bucket seats and better brakes. The Regal sedan has been dumped. New grilles are popular and extend to the front-drive Century as well. Changes on the LeSabre are minimal while the new front-drive Electra, unveiled last spring as an '85 model, is unchanged. A touch-screen electronic control center is optional on the Riviera.

Oldsmobile drops the X-body Omega, but unveils its version of GM's sharp new N-body car, the Calais Coupe. The Firenza, Oldsmobile's rendition of the GM subcompact J-car, offers the port-injected 2.8-liter V-6 as an option.

Biggest car in the Olds showroom is the Delta 88 now that the division's rear-drive 98 is off the lot. The front-drive 98, introduced last April as an ' 85, moves ahead ''as is.'' The front-drive Toronado, originally introduced in the 1960s but revised in '79, gets a new front end.

Grand Am joins the Pontiac fleet with base 4-cylinder power, but with a perky V-6 as an option. The front-drive Pontiac 6000 has few visual changes in '85 with the low-volume 6000 STE (Special Touring Edition) getting more power - the 145-h.p., 2.8-liter V-6 as standard engine, an option in the standard 6000.

Pontiac will offer V-6 power in the Fiero to beef up its performance, an option on the Sport and SE models. A GT version is due out in '85.

As for the subcompact 1000, Pontiac's clone of the Chevrolet Chevette, ho hum.

To sharpen its identity as a Pontiac, not just as a J-car, the Sunbird sheds the figure 2000. Bonneville and Grand Prix are essentially unchanged from last year, and so is the rear-drive, large-size Parisienne.

Cadillac, like Buick and Oldsmobile, introduced its ''first of the '85s'' eight months ago, the front-drive Fleetwood and DeVille. The rear-drive versions are dropped for '85. GM has also sharply downsized its limousine. Seville and Eldorado are unchanged for '85.

Cimarron, which began life as one of GM's anemic J-cars, moves closer to the Cadillac mold with new front-end styling and restyled alloy wheels. Many people don't rate it as a real Cadillac, however. A 2.8-liter V-6 is optional.

Tomorrow: Ford's '85 lineup