And now the least famous member of the popular Ford duo-the Mercury Sable.

Sable was introduced along with its partner from Ford at the same time, Dec. 26, 1985.

Like Taurus it had two shortcomings: It needed a somewhat larger, more powerful optional engine to complement the standard 3-liter V-6 and as a family sedan it needed antilock brakes as an added insurance policy.

But Sable had one problem Taurus didn`t have: It was the less publicized of the front-wheel-drive, midsize twins from Ford. Sable always got second billing as in ``Taurus and Sable.``

Sable deserves better treatment, especially now that like Taurus it offers the options of a 3.8-liter V-6 engine as well as antilock brakes. And throw in a driver`s side air bag as standard. Yes, standard, even though some customers who`ve called Ford`s toll-free customer service hotline have been told an air bag is optional in Sable. Mercury officials vow the folks manning the phone will be informed of the mixup.

The FWD Sable sedan comes in GS and LS versions. We test drove the 1990 LS sedan.

The 3.8 V-6 makes a noticable difference in performance starting up from the light, accelerating in the merger ramp, or when pulling into the passing lane. The 3.8 has the same 140 horsepower as the 3-liter V-6, except that the 3.8 delivers that power at 3,800 r.p.m. and the 3-liter not until 4,800 r.p.m. That means quicker response to pedal pressure from the 3.8. You get up to speed at the beginning of the merger ramp, not at the end.

For the power you pay a small price, an EPA rating of 19 miles per gallon. city/28 highway versus a 20/29 rating with the 3-liter V-6. You also pay another price-$555 for the option.

ABS is a $985 option that`s well worth the investment, even if it really counts only once. ABS means quick, sure stops regardless of highway surface as sensors tell the on-board computer to pump the brakes to avoid wheel lockup. We didn`t have to use ABS at all during the test, but knowing the system was available in reserve still added to the daily driving pleasure.

While Sable has overcome its two major shortcomings, there still is one annoyance we wish Mercury would eliminate: the feeling of weight in the wheel. Sable isn`t petite. It tips the scales at about 3,200 pounds. It feels every bit that amount despite the addition of optional ($104) variable assist power steering. With the variable feature you get more steering assist when you need it, such as at low speeds when pulling into a parking space, and less assist when you don`t need it, such as at cruising speed on the expressway.

The larger 3.8 V-6, ABS, and air bag hardware all combined to add poundage to the car. The Sable`s steering system felt as if it could use even more power assist in those low speed maneuvers, or trim off a hundred pounds or so.

Sable has good room, above average comfort, and more than am ple trunk room.

It also has a few goodies worth noting, such as dual sun visors-a regular visor you can pull out to block the sun coming in the driver`s side window, and a plastic visor underneath that you can keep in place along the windshield to continue protecting your vision from the sun directly ahead.

Another neat feature is the arrow with the fuel gauge in the instrument panel that points to the passenger side so that you have no doubts where to park when pulling up to the gas pump.

Ford designers also were attuned to the times when they came up with the center console and dual cup holders, coin holder and hidden stowage tray.

The insta-clear heated windshield that removed the evening`s coating of ice in just seconds was appreciated, too, though at $250 it`s a luxury equal to a back seat full of window scrapers.

Base price of the Sable LS is $16,011, but you can reach $20,000 easily if you equip your car like Mercury did the tes vehicle.

Standard features include air conditioning, tinted glass, electronic AM- FM stereo, dual remote control mirrors, tilt steering, 4-speed automatic with overdrive, power brakes and power steering (variable assist optional).

Added to the test car was a preferred equipment package for $3,036 that included cruise control; rear window defroster; upgraded 15-inch all-season tires (14-inch is standard); leather-wrapped wheel; power locks, seats and radio antenna; floor mats; bodystripes; keyless entry; electronic instrument cluster; and cast aluminum wheels among the major goodies.

Then there was the luxury touring package that added $2,215 and consisted of ABS brakes, power moon roof and leather seats. Add a JBL sound system for $488, compact disc player for $491 and clearcoat paint for $188 and the sticker rose to $23,233 before option package discounts that brought the final sticker to $22,033, plus $450 for freight.