Used 2008 Ford Shelby GT500 Coupe

Once in a while, a vehicle comes along that rewrites the rules on what is possible in a road car. It performs beyond what can reasonably be expected and establishes a high-water mark that will not be met for years, even decades.

In the literal sense — as a performance car — the 2008 Ford Shelby GT500KR does not meet this standard. After all, the Chevrolet Corvette Z06, Dodge Viper SRT10 and Nissan GT-R will all outperform the Mustang GT500KR for the same money, or even less.

Yet as a concept — as a means to an end — the GT500KR works brilliantly.

Friends With Benefits
The 2008 Ford Shelby GT500KR (the KR suffix stands for "King of the Road") is a celebration of the 40th anniversary of the original 1968 Shelby GT500KR. It starts as a Mustang GT500 that has been fettled by Ford's SVT group, and then the rolling chassis is shipped to Shelby's facility in an industrial park adjacent to Las Vegas Motor Speedway, where many of the KR-specific bits are installed.

You might not notice at a glance the KR's bespoke forged wheels, its sticky tires or a ride height that's 0.79 inch lower in front and 0.6 inch lower in the rear. More apparent is the KR's comprehensively ducted and vented hood, which funnels air to the engine's conical air filter from Ford Racing. Too complex to make in metal, the GT500KR's hood is constructed of carbon fiber by the same supplier that manufactures parts made of the lightweight yet strong composite material for the Corvette ZR1 and Dodge Viper ACR.

A revised engine calibration with more aggressive spark mapping takes advantage of the KR's requirement for only premium fuel, while a less restrictive exhaust goes bwopbwopbwop at idle and then gives way to a pronounced gurgle at part throttle. If the Jetsons drove a muscle car, this is what it would sound like.

These changes liberate an additional 40 horsepower and 30 pound-feet of torque from the GT500's supercharged 5.4-liter V8, bringing the KR's output to 540 hp and 510 lb-ft of torque. A shorter 3.73:1 final drive and short-throw shift linkage round out the upgrades to the powertrain.

Ford reckons the KR will run to 60 mph in 4.3 seconds and click off the quarter-mile in 12.1 seconds at 115 mph. These numbers are respectively 0.2 and 0.7 seconds quicker and 3 mph faster than those achieved by the GT500 in Ford's testing.

Finishing What They Started
In the name of better turn-in and more grip from the Mustang chassis, SVT has made another pass at the GT500's suspension. Slightly stiffer springs and a lighter-rate front antiroll bar are fitted, and the rebound damping is nearly twice that of the GT500. A more aggressive front-end alignment adds negative camber and removes the toe-in found at the front of the GT500, helping the softer-compound (a 180 treadwear rating compared to the GT500's 220) Goodyear Eagle F1 Supercar tires to bite the tarmac with increased tenacity.

The efforts made to improve the KR's aerodynamic behavior at high speed are intriguing, because they're focused on balance rather than outright downforce. While the KR wears a revised splitter that reduces front-end lift by 31 percent and drag by 3 percent compared to the GT500, the rear wing's reduced angle of incidence fractionally reduces drag and actually increases lift at the rear axle relative to the GT500.

On the streets outside Salt Lake City, Utah, where Ford invited us to drive the KR, it's hard to go fast enough to detect this Mustang's newfound stability and harder still to blend into the traffic. If you don't get the attention of your commute-hour companions with the twin stripes on the bodywork, the complex hood complete with hood pins and the garish badging, the roaring exhaust will certainly turn their heads, as it makes even casual getaways sound like an invitation to street-race. Rough roads reveal the limitations of the live axle's unsprung weight, yet overall the KR is street-friendly enough to be a daily driver.

It's Miller Time
Ford put us on Miller Motorsports Park (MMP) to test the KR's handling mettle. MMP — a world-class racetrack in the middle of the Utah desert about 45 minutes southwest of Salt Lake City (home to a racing series featuring the Mustang FR500S) — has little in the way of elevation changes. Yet the 4.4-mile West Loop features 10 turns with several long steady-state corners with late apexes and off-camber sequences that comprise a demanding test of handling and braking. It's a great track, and the chance to drive the KR back-to-back with the GT500 taught us a lot about this new Mustang.

Right away, the shift linkage for the KR's six-speed manual transmission is more positive and moves through the gates with added precision. Dive and squat in the chassis setup are better controlled, inspiring confidence that is bolstered by the supercharged V8's wide power band with its relatively flat torque curve. The KR's front end bites more sharply at turn-in and with less initial understeer than the GT500, so it feels far more agile.

Ford claims the KR has churned around the skid pad with a 1.00g result and has run the slalom in 71.7 mph in its preliminary testing. Perhaps Miller's track is less sticky than Ford's skid pad, or our seat-of-the-pants g-meter has lost its calibration, but the KR didn't feel as though it was generating quite as much grip through the turns at MMP as Ford thought. It was certainly cornering faster than the GT500, though.

Of all the KR's changes, the shorter final-drive ratio makes the most difference and really makes this Mustang come alive. Powering out of turn six, a late-apex right-hander taken in 3rd gear, the KR pulls with a vigor not found in the GT500. Where the KR flings itself into the braking zone for the next corner with deceptive quickness, the GT500's tall gearing makes it feel soggy.

You never forget that the KR is a nose-heavy, 3,879-pound car, and the sense of inertia — the reluctance of mass to be persuaded into movement — is palpable. The Mustang's brakes are the primary victim of this interplay, and despite the addition of front brake cooling ducts (tossed into the trunk of every KR for installation by its owner), fade is the inevitable consequence.

KR Stands for "King's Ransom"
There is no denying that the 2008 Ford Shelby GT500KR is superior in every performance context to the Ford Shelby GT500, and its guttural exhaust note and firmer ride quality are perfectly acceptable for daily use. In terms of a complete package, the GT500KR is what the GT500 should have been in the first place.

This is why it is difficult to view the GT500KR without a blend of cynicism and admiration. The KR's attendant improvements are relatively modest in light of the thirty-five thousand dollar premium the KR commands over the $45,000 GT500, a sum that swiftly swings a knee into the groin of the Mustang's mission of "affordable performance."

The Shelby faithful won't care. Just 1,000 GT500KRs will be produced for 2008, and once the remaining 700 or so are produced in 2009, the KR is done. Even at the KR's MSRP of $79,995, including destination charge and gas-guzzler tax, the KR's collector-car appeal means Ford and Shelby will sell every single one.

Certain dealers know this, too, and are charging outlandish markups that bring the asking price to more than $100,000.

Some would call this behavior on the part of Ford and its dealer network egregious or greedy. We call it shrewd business sense and knowing one's customers.

Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.