Ford’s commitment here goes only so far, as evidenced by the absence of RS or ST badging; Ford Performance’s handling experts didn’t have their way with the car. Steering feel is lackluster, and the brake pedal has a long travel and little feedback. And the car feels every bit as heavy as the 4128 pounds measured on our scales. Ford needs to make haste with its lightweighting research, a field where General Motors is doing much better. All that mass leaves an overall impression that the Fusion Sport amounts to a smaller version of the Taurus SHO, a car whose days are numbered, and even the performance figures are similar.

When driven aggressively, there are hints of torque steer before the AWD system activates and moments of hesitation where you can feel the car sorting out, just for a moment, which gear to choose and how much steering effort should adjust to conditions. All this keeps it from being a sharp-edged driver’s car, although, on paper, it’s a budget Audi S4. To deliver on that promise, besides putting the car on a diet, would require a less fuel-economy-minded all-wheel-drive system with more rearward bias of torque distribution and a lot more attention to the niceties of control feel and precision.

As you may recall, this long-term test is different. Wanting to see us cover almost the entire IS model line rather than just one car, Lexus sent us an IS 250 rear-wheel drive model to start and has now swapped it out for an IS 350 all-weather drive (in Lexus speak) model. This one will swap out for a rear-wheel drive IS 350 F Sport in a few months.

In the meantime, let’s talk about the new ride. In addition to a long list of options not spec’d on the 250, the 350 AWD packs a bigger engine and all-wheel drive. 102 extra horsepower courtesy of an extra liter of displacement makes for a substantial difference in performance, as does AWD traction. The result: 5.3 seconds to 60 mph, nearly two seconds quicker than the 250’s 7.2-second sprint.

We didn’t see it coming because, on any other type of road, the IS clearly exhibits Lexus’s traditional top priority: serenity. On typical highway surfaces, minute twitches in the steering wheel and nearly imperceptible shifts of the body offer only the slightest hint of what lurks within. But charge into a series of quick bends and the IS completely changes its character. Turn-in is crisper in the Lexus than in either the BMW or the Cadillac, a fact borne out by its first-place slalom finish in spite of a mediocre skidpad performance. More important, the Lexus is utterly imperturbable. Bumps that send other cars skittering off-line or scrambling to maintain their course are absorbed and dispatched, but not kept completely hidden from the driver.