The speedometer tells the story. The circular loop starts at 0 m.p.h. and doesn't stop for about 180 degrees until it reaches 140 m.p.h. This is not an economy car. Nor is it the industry mileage champ or even a runner-up. It's the Taurus SHO, the muscle-bulging performance version of the Ford family sedan, with power supplied sumo-style, thanks to Yamaha of Japan and its 3-liter, 24-valve, 220-horsepower V-6 under the hood. Japan bashing only goes so far at Ford-obviously until it reaches 220 horsepower. While only a five-speed manual is offered now, reportedly a four-speed automatic will become available this fall for the 1993 model year, which will make SHO available to the masses. The five-speed manual is a smooth-shifting unit when a dry and open road stares you in the windshield. The five-speed is far less balky than in the past, thanks to the switch to a solid rod from the prior cable-shifting mechanism. Yet while SHO was built for go, we found ourselves on the expressway with the needle pointing at 10 m.p.h.-130 m.p.h. short of Utopia. The weather was lousy, the roads covered with a thin layer of snow. On this day, SHO is for slow. A 140-m.p.h., 24-valve, 220-horsepower, V-6-powered car makes little sense in a 10-m.p.h. rush-hour crowd. The power potential meant little to the drab Plymouth Reliant merging at Dempster Street directly in front of the muscular Ford. SHO's redeeming grace is that it's a Taurus, a roomy, comfortable, freshly styled for 1992 midsize sedan with above-average ride and more-than- respectable handling. The SHO first appeared in 1989 as the high-performance version of Taurus. The criticism since then has been that SHO looked just like the regular Taurus, unlike the SSE performance version of the Bonneville sedan at Pontiac, which was decidedly different in appearance. For '92 the Taurus was restyled, and that gave Ford a chance to give SHO a bit different look from the normal sedan. SHO now sports special color-keyed bodyside and rocker-panel moldings, flared mud spats, a different grille with integrated fog lamps, a different rear bumper and 16-inch aluminum wheels. To improve ride and handling, the suspension was retuned and now incorporates stiffer springs and larger-diameter stabilizer bars. The larger 16-inch tires and nitrogen-gas-pressurized front and rear shocks complement the package. For safety, SHO offers four-wheel disc brakes with antilock. A driver- side air bag is standard, a passenger-side bag is optional ($488). With ABS and the air bags, you don't have to hide SHO in the garage when snow starts falling, though you don't deliberately set out for a 300-mile journey behind its wheel if you don't have to. The SHO starts at $23,772. Options include $491 for a digital disc player.