There are very few survivors left among the big, conventional rear-drive cars. And next year there will even be fewer. In fact, this column has been tolling the bell for so many departed big cars over the past couple of years that it is beginning to sound like a carillonneur playing the carioca.

The latest car set to ride into the sunset - but fortunately, very much alive until the end of the 1985 model year - is the Buick LeSabre. It's the biggest and heaviest car left in the Buick lineup and the one remaining car that carries all the features that were once sought in a Buick - luxury, boulevard ride, good power and an imposing presence. But downsizing, resizing and economizing have - as anyone who hasn't been stranded on an ice floe for the past decade knows - have changed the American automobile considerably.

Now big cars are lighter in weight, have front-wheel drive and smaller engines and are quite space efficient inside. This brief description could, of course, apply to the Buick Electra which had been slightly larger than the LeSabre until it got the treatment last year and was introduced as an early 1985 model. But Buick can't have what had been traditionally its biggest car in the lineup be smaller than what traditionally had been its second largest car. For the 1986 model year, the LeSabre will be similar in concept and size to the Electra. This, of course, could mean one of two things for Buick lovers - wait until next fall for a brand new model or, if you want a big, traditional Buick, grab it now while the grabbing's good.

The test car, supplied by Kelly Buick, State Road, Emmaus, was a stately looking four-door sedan done up in dark metallic blue with a tan vinyl top, that looked large enough to challenge mastodons. The Goodyear blimp might not fit in the interior but with a volume of 110 cubic feet, six adults will have room to rattle around. And all would be able to throw their luggage in the deep and wide 21-cubic-foot trunk.

For basics, the LeSabre has a wheelbase of 115.9 inches; overall length, 218.4 inches; width, 75.2 inches; height, 56.7 inches, and curb weight, 3,750 pounds. Take a second look at these figures because you won't be seeing numbers like this for too long. Interior figures are even more impressive. In the front seat, leg room measures 42.2 inches; head room, 38.2 inches; shoulder room, 60.3 inches and hip room (sounds like someplace Wolfman Jack would retreat to), 55 inches. In the rear seat, leg room is 38.9 inches; head room, 38.2 inches; shoulder room, 61 inches, and hip room, 55.3 inches.

The seats of the test car featured plush, padded upholstery. Sitting in the driver's seat was like stretching out in an easy chair at home. In fact, things were so good I was even comfortable sitting in the back seat. With thick carpeting on the floor, a padded headliner and plenty of sound-deadening material throughout the car, one could drive, or ride around in, the LeSabre oblivious to the outside world - or, at least, its noise. Super quiet.

Although large in size, the LeSabre is an easy car to drive. But, with all of its power equipment it should be. Drop the four-speed automatic overdrive transmission in gear, press on the accelerator and you are away. There's a lot of distance to the front bumper and even more space to the rear of the car, but with its traditional styling, judging those wide open spaces is not difficult. Sure, there's more to look after than in driving a subcompact but with an open mind and a little practice, anyone will be able to feel at ease driving this car.

The test car rode comfortably, something that should be expected from a big Buick, but did not feel like a giant marshmallow, something that could be said of the older Buicks. The LeSabre features coil spring suspension on all four wheels, typical of General Motors big car suspensions. However,B ick had four wheel coil spring suspension back in the late 1930s and at that time it was quite a rare configuration. Although Buick makes no claims that the LeSabre is a sports sedan, handling isn't that bad. But if one does want a little more in lateral control, two optional suspensions are offered - heavy duty and Gran Touring. For some reason, though, I just can't picture a LeSabre buyer going for the sportier suspensions. Unless, of course, someone is planning to do towing. With the right equipment, the LeSabre can tow a trailer weighing up to 5,000 pounds.

A big conventional car like the LeSabre is best appreciated when traveling the distance over the highways. Nothing wrong with driving it around town, but it is just much better suited for the open road. I gained much respect for the test car when I drove it more than 150 miles through heavy, heavy rains with some hail thrown in for a little frosting. Not that this is the only type of car that can be driven in these conditions, but I just felt so much safer with all its weight holding it on the road and all that sheet metal surrounding me. All-season radials (standard equipment) also helped out.

The test car was powered by the optional 307 cubic inch (5.0 liter) V-8 with four-barrel carburetor. This engine is produced by Oldsmobile Division and is remotely based on the old Rocket V-8. As far as engines go, this ranks with the best. Although this engine, like the rear drive LeSabre, doesn't have that much longer to go, it had several refinements this year for better fuel economy and smoother running. There were modifications to the combustion chamber and a more centrally located spark plug to provide a faster burn. Also, friction is lessened by the use of roller valve lifters, and revisions to the camshaft contour allowed a reduction in idle speed. There were also some changes to the computer control system.

Obviously these changes weren't done to soupup the engine since it still has the same 140 horsepower rating of last year. Performance, though, is quite respectable. Putting the pedal to the metal won't throw you into the back seat but it will get you out of harm's way. The test car was equipped with the optional four-speed automatic, which shifted smoothly and no doubt contributed to better fuel mileage. The test car averaged 13 miles per gallon for city driving and 22 mpg over the highways. Not bad at all. Since the fuel tank holds 25 gallons, there will be a long way between fill ups.

Standard engine for the LeSabre is the 231 cubic inch (3.8 liter) V-6 with two-barrel carburetor. There is also an optional 350 cubic inch (5.7 liter) V- 8. For all around use, though, I would recommend the 307 V-8.

Base price for the test car - a top of the line Limited Collectors Edition, which it could very well be - was listed at $12,154. The level of trim was high and there were many standard features including power steering and brakes, all-season radials, 50/50 notchback seats, driver's 6-way power seat, AM radio, tinted glass and dual chrome outside mirrors. With options totaling $3,052, a dealer's protection package at $299 and a destination charge of $475, total price on the test car came to $15,980. Options included: air conditioning, $775; 307 V-8, $490; power windows, $270; power door locks, $180; vinyl top, $185; rear window defogger, $145; four-speed automatic, $175; wire wheel covers, $199; tilt steering, $115; electronic AM-FM radio, $344, and power antenna, $65.