I haven't had much use for the Jaguars of the last decade or so.

Jaguar Cars' XJ40 sedans, launched in 1987, were to my eye the apogee of the let's-make-it-square design philosophy prevalent for most of the '80s. If nothing else, Jags were supposed to be luscious, maybe even provocative, of line. Those blocky XJ40s couldn't have been provocative if custom-fitted with a Frederick's of Hollywood car brassiere.

Moreover, while Jaguar's faithful inline 6-cyl. and more famous V-12 engines have long provided foundation for agreeable - if not always inspirational - drivetrains, for me it has been sloshy suspensions and crotchety handling that imbued the perception that Jaguars of late plied much more on emotion than substance.

Things changed when new owner Ford Motor Co. planted its fingers in Jag's product-development pie. Soon, Jaguar's standing reputation for iffy reliability and scratchy build quality improved. And last year's round-headlight restyling recalls the traditional streamlined aesthetic that Jaguar absolutely needed to reaffirm.

The most important facet of the '95 makeover, however, was that the new Jaguar sedans rode on the X300 platform, which tendered quantifiable dynamic improvements over the XJ40. The 4L DOHC 6-cyl. engine was substantially revised, developing 245 hp, while the hoary 6L SOHC V-12 has 313 hp and a gigantic 353 ft.-lbs. (479 Nm) of torque to offer.

Dynamically, then, Jaguar sedans were finally on solid footing versus their accomplished BMW AG 7-series and Mercedes-Benz AG S-class rivals - and the handsome new sheetmetal re-established Jaguar's penchant for evocative styling, the one aspect of car building to which the calculating Germans seldom attach any true priority.

The only real rap left was that the new X300 package was, well, a tad short on passenger space, particularly in the rear. Not a good thing for a prestige luxury car.

Well, the X300 sedans were launched just last year, so industry smart guys speculated that given Jaguar's track record, the passenger-room thing would be put right in, oh, a decade or so.

Not so. For 1996, Jaguar's XJI2 and Vanden Plas sedans are offered with a long-wheelbase option that slides an extra 4.9 ins. (12.5 cm) into the wheelbase, all of it aft of the B pillar.

So the particulars are thus: the new long Jags possess a wheelbase of 117.9 ins. (299 cm), compared with the 113-in. (287 cm) standard-wheelbase models. Overall length increases by that same 4.9 ins. The all-important rear-seat legroom measurement is increased by 4.5 ins. (11 cm).

Jaguar claims all this amounts to less than an inch of rear legroom difference between its stretcher and Mercedes' S-class; the new long-wheelbase 7-series BMWs, the Jag folks admit, are positively monstrous in the rear. But such measurements can prove keenly deceptive, so the only real proof is to ride back there.

I've been ferried in the rear of all three cars. BMW's and Mercedes' long cars a cavernous for rear-seat passengers; I can only judge the Jags as guardedly roomy.

But the point is probably not that critical. Functionally, there's definitely more room available than in the standard wheelbase Jaguar sedans - astoundingly categorized as midsize cars.

The long-wheelbase Jaguars command an additional 48 lbs. (22 kg) in overall weight and an extra 200-odd parts, but they're built on the same assembly line as the standard models. The stretch necessitated new rear doors, new windows for both the doors and the rear screen (all window thicknesses have been increased from 0. 16 ins. [4 mm] to 0.20 ins. [5 mm] in the interest of quieter cruising, incidentally) and a new, more bulbous roof panel that affords an extra half-inch of front and rear headroom.

What the X330 stretch didn't change, thankfully, is the entertaining dynamics first exhibited in the X300 sedans. For starters, the almost ideal 51%/49% front/ rear weight distribution remains unsullied by the extra inches. Handling, then, is surprisingly neutral in all but the tightest of corners, aided by a speed-sensitive power steering calibration that is absolutely spot-on for a car of this nature.

The revised drivelines are equal to anything the Germans offer. The 6-cyl. Vanden Plas wails with plenty of gumption, the XJ12 pounds out power in abundance. The six is connected to the rear wheels by a ZF four-speed automatic, the big engine by General Motors Corp.'s 4L80-E fourspeeder. Both deliver creamy shifts when the right foot is docile and devilishly crisp changes when shown the whip. The sport/ norinal transmission modes actually work and Jaguar's manual-shifting arrangement remains one of the industry's best.

Jaguar expects sales of the long-wheelbase cars (prices to be setjust before the Oct. 4 onsale date) to be roughly 25% to 30% in the U.S., which now takes more than half of the company's total production.

Tellingly, Jaguar's U.S./Canada sales volume in the first six months of this year are up 29% over last year (Jaguar racked up total sales of 6,819 units through July) and Jaguar Cars U.S.A. President Mike Dale talks of yearly sales here of 20,000 units in the foreseeable future.

With products like the new XJ12 and Vanden Plas, stretched or not, that prediction doesn't seem inappropriate. These formidable new sedans convince me that Jaguar is once again peddling more than just tradition.