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Tuesday, August 26, 2008

America's Best Handling Car Part 1

By Matt Stone, Kim Reynolds, Arthur St. Antoine, Frank Markus
Photography by William Walker, Julia LaPalme, Brian Vance

STAY TUNED: Part two of our Best Handling competition will run this Wednesday (Aug. 27) and the winner story will run this Friday (Aug. 29). We'll have more videos throughout the week on each car.

We gazed into a maze of wires and circuit boxes and asked that question 16 months ago as we launched perhaps the most rigorous and ambitious regimen of racetrack and airstrip tests mere auto scribblers ever subjected 10 cars to. It responded with 420 megabytes of data that, along with subjective notes scrawled in logbooks and jabbered into voice recorders, revealed an indisputable answer-the Porsche 911 GT3. All that data also helped illustrate how such nuanced elements of handling as transitional behavior, path accuracy, chassis composure, steering and brake feel, and even cockpit ergonomics dovetail with conventional metrics like lateral grip, cornering power, and track-lap times to produce vehicle handling that delights (or dismays) the driver.

As the ink was drying on that story, gadget-guru Reynolds was already dreaming up new instruments and tests to help us delve even deeper into the mystery of what makes a great-handling car, so we've decided to make this an annual event pitting the newest corner-carvers against the reigning champ. This year that mission was stymied by our utter inability to beg, borrow, or steal a GT3, GT3 RS, or GT2, however, so an all-wheel-drive 480-horse 911 Turbo is standing in as proxy.

The contenders, starting from the humble front-drive end of the field include Chevy's turbo-direct-injected Cobalt SS coupe and the Mini Cooper S. Front-engine/rear-drivers include a Mazda RX-8 with the new R3 handling package, BMW's rev-happy V-8 M3, Ford's highest-performing MustangDodge's race-ready Viper ACR. Front-engine all-wheelers include the new MitsubishiNissan GT-R. Contesting the mighty 911 Turbo in the mid- or rear-engine supercar class is Audi's stunning R8. ever, the Shelby GT500KR, and Evolution MR and newer

So with that preamble we'll head for the abandoned runways at El Toro Marine Air Station to try out Reynold's new gear and tests, then return to Mazda Raceway at Laguna Seca for hot laps with pro shoe Randy Pobst. We're foregoing the road loops to free up more space to explain our results. Should reigning Porsche be preparing a poison apple? Read on.


Price*: $120,700
Driveline: Mid engine/4.2L V-8/420 hp/317 lb-ft/6-sp auto-cl man/AWD
Suspension, f;r: Control arms, coils, adjustable shocks, anti-roll bar; control arms, coils, adjustable shocks, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3654 lb (44/56%)
Tires f;r: 235/35R19 91Y; 295/30R19 100Y Pirelli PZero
15.0-in vented/8-piston; 14.0-in vented/4-piston, ABS

Price*: $63,075
Driveline: Front engine/4.0L V-8/414 hp/295 lb-ft/7-sp auto-cl man/RWD
Suspension, f;r: Struts, coils, adjustable shocks, anti-roll bar; multilink, coils, adjustable shocks, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3678 lb (51/49%)
Tires f;r: 245/35R19 93Y; 265/35R19 98Y Michelin Pilot
14.2-in vented, drilled/1-piston; 13.8-in vented, drilled/1-piston, ABS Sport PS2

Price*: $23,490
Driveline: Front engine/2.0L I-4/260 hp/260 lb-ft/5M/FWDd
Suspension, f;r: Struts, coils, anti-roll bar; torsion beam, coils, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 2952 lb (60/40%)
Tires: 225/40R18 92Y Continental ContiSportContact 2
12.4-in vented/4-piston; 11.5-in vented/1-piston, ABS

Price*: $100,976
Driveline: Front engine/8.4L V-10/600 hp/560 lb-ft/6M/RWD
Suspension, f;r: Control arms, coils, adjustable shocks, anti-roll bar; control arms, coils, adjustable shocks, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3415 lb (49/51%)
Tires f;r: 295/30R18 94Y; 345/30R19 105Y Michelin Pilot
14.0-in vented, slotted/4-piston; 14.0-in vented, slotted/4-piston, ABS Sport Cup

Price*: $79,995
Driveline: Front engine/5.4L supercharged V-8/540 hp/510 lb-ft/6M/RWD
Suspension, f;r: Struts, coils, anti-roll bar; live axle, coils, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3886 lb (58/42%)
Tires f;r: 255/45R18 99W; 285/40R18 96W Goodyear Eagle F1 Supercar
14.0-in vented/4-piston; 11.8-in vented/2-piston, ABS

Price*: $32,580
Driveline: Front engine/1.3L 2-rotor Wankel/232 hp/159 lb-ft/6M/RWD
Suspension, f;r: Control arms, coils, anti-roll bar; multilink, coils, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3056 lb (53/47%)
Tires f;r: 225/40R19 89W Bridgestone Potenza RE050A
12.7-in vented /2-piston; 11.9-in vented/2-piston, ABS

Price*: $23,350
Driveline: Front engine/1.6L turbo I-4/172 hp/177 lb-ft/6M/FWD
Suspension, f;r: Struts, coils, anti-roll bar; multilink, coils, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 2680 lb (62/38%)
Tires: 205/45R17 84V Dunlop SP Sport 01
11.6-in vented/4-piston; 10.2-in solid/1-piston, ABS

Price*: $38,915
Driveline: Front engine/2.0L turbo I-4/291 hp/300 lb-ft/6-sp auto-cl man/AWD
Suspension, f;r: Struts, coils, anti-roll bar; multilink, coils, anti-roll bar
Brake discs/Calipers, f;r:Curb weight (dist f/r):
Tires: 245/40R18 93Y Yokohama Advan AIE
13.8-in vented/4-piston; 13.0-in vented/2-piston, ABS 3647 lb (57/43%)

Price*: $70,475
Driveline: Front engine/3.8L 2-turbo V-6/480 hp/430 lb-ft/6-sp auto-cl man/AWD
Suspension, f;r: Control arms, coils, adjustable shocks, anti-roll bar; multilink, coils, adjustable shocks, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3868 lb (55/45%)
Tires f;r: 255/40R20 97Y; 285/35R20 100Y Dunlop SP Sport 600 DSST
15.0-in vented, drilled/6-piston; 15.0-in vented, drilled/4-piston, ABS

Price*: $134,465
Driveline: Rear engine/3.6L twin-turbo flat-6/480 hp/460 lb-ft/6M/AWD
Suspension, f;r: Struts, coils, adjustable shocks, anti-roll bar; multilink, coils, adjustable shocks, anti-roll bar
Brake discs/Calipers, f;r:
Curb weight (dist f/r): 3547 lb (39/61%)
Tires f;r: 235/35R19 87Y; 305/30R19 102Y Michelin Pilot
13.8-in vented, drilled/6-piston; 13.8-in vented, drilled/4-piston, ABS Sport PS2

Martin Mull once quipped, "Talking about music is like dancing about architecture." Writing about vehicle handling turns out to be just as tricky if you only have a handful of traditional skidpad, slalom, lane-change, or hot-lap times to work with. Experts who spend their lives wringing cars out on corporate proving grounds or racing circuits can author SAE papers on the subject using an arcane vocabulary all their own. The rest of us yearn for more scientific analysis to prop up our seat-of-the-pants predilections -- especially when attempting to rank 10 of the best-handling cars in the land.

Toward that end we'll mount our Racepak GPS receiver and datalogger securely to the passenger footwells of each contestant so that its accelerometers and gyro can accurately register a car's every wiggle and twitch. Other sensors will report the steering-wheel angle, body ride heights (for pitch and roll information), and the ride vibrations sensed by the driver through the seat. Then each car will head out onto the mirror-flat airport tarmac to execute a variety of peculiar maneuvers -- like gently weaving back and forth at 50 mph to measure on-center steering feel, gradually accelerating from a walking pace to max-lat around a circular skidpad to learn how the tires behave en route to their limits of adhesion and jerking the wheel at 50 mph to measure chassis-response time. We'll also lean on the extra sensors to provide deeper insight into each car's behavior in MT's exclusive figure-eight test and through a modified emergency lane-change maneuver.

Sifting through the resulting megabytes of science gathered over two long days at the old El Toro Marine air base in Southern California should help us all understand exactly why each car bobs and weaves the way it does when they take to the twists at Laguna Seca. Then we'll be ready to pick a winner.

Best Handling Comparison Preparation

1. On-Center Sensitivity

Although the word "handling" might seem like a singular, indivisible characteristic -- "that's a great-handling car," we might say -- its indivisibility is an illusion. The truth is, handling is a melding of a great many distinct characteristics. And each can be exposed, facet by facet, if you shine a light on them in just the right way. This first section of our story comes from two days of dogged testing for all manner of these vehicle dynamic clues on the big runways of El Toro. And the first among these might appear so basic it borders on irrelevant. But it's just the opposite.

Unless you live at the bottom of San Francisco's Lombard Street and work at the top of it, your dominant experience with handling is on-center feel. Just a few degrees of steering-wheel angle, left and right off-center are often all you need while traveling enormous distances. Is it sloppy or tinglingly precise?

Our test for this consisted of driving at 50 mph and repeatedly tilting the wheel off-center at an assortment of turning rates, from casual to quick. Meanwhile, our steering-angle sensor and lateral accelerometer were logging away at 100 times per second. The results we're showing here represent how many degrees of steering angle were needed to produce a subtle 0.1 g of lateral acceleration, at two steering rates -- a slowish 50 degrees per second and an aggressive 150 degrees per second. The Mini's stubby length, low weight, and quick steering ratio made it the sensitivity king during casual steering. But interestingly, the Nissan needs the smallest steering angle to hit our 0.1g bogey when you really crank the wheel. Compared with the Nissan, the Mustang needed over 50 percent more steering angle, while the Cobalt required more than twice the Mini's angle during slow-rate turning.

Note that a car can have excessive on-center sensitivity -- race cars being an extreme example. Our dual winners, the Mini and Nissan, seem just about right, though.


2. Skidpad

Ordinarily, a couple clockwise and counterclockwise orbits around the skidpad are all it takes to produce the interesting, but singular handling fact we call maximum lateral acceleration. That's ordinarily.

However, with additional instrumentation and a certain method to our madness, the circle can reveal a great deal more. Tracing its perimeter first at a walking pace, and then at gradually quicker speeds, the shape of the car's steering angle-versus-lateral acceleration curve can be telling. For instance, when does its growing understeer cease to be linear and begin to fade into nonlinearity? And how do the front tires behave near their limits? Ideally, the curve has a nice rounded top so that, if you quickly twist the steering wheel past the grip peak, you'll instantly picture right where it is.

Note how difficult this is in the Shelby KR, RX-8, and Cobalt SS, while the Viper's peak is perhaps too abrupt. The Dodge is also the most resistant to body roll (it lists the same 1.8 degrees as the Audi, but at a higher cornering rate). Last, we sampled each car's steering effort at exactly 0.5 g. Highest? A stiff 6.1 pounds for the Nissan, while the BMW needed a feathery 2.2 pounds.

3. Step Steer

When you turn a car, you're actually instigating a sequence of three motions. And their timing and relative interplay are about as close as you can get to knowing the Holy Grail of handling behavior. Motion One is turning the front wheels -- that's what causes the car to begin rotating, or what we call yawing. It's this yawing that triggers Motion Two, lateral acceleration, as the rear tires find themselves angled relative to the car's path and begin to contribute a side force. The rear tires are fractionally Johnny-come-latelys to the cornering party, so to speak. How the car responds to lateral g? Motion Three, body roll. See if you can perceive all three motions next time you turn into a corner.

What you see below is how each of our cars expressed these three behaviors, the length of their bar graphs representing the time it takes for each of them to stabilize. And, by the way, we've ranked them here according to yaw, as this is the first thing you're likely to notice. It's as good a gauge of "response" as anything. So what's the ideal sequence of events?

Well, body roll should be completed fairly quickly after steady-state lateral g is achieved. And naturally, none of the whole sequence should take too long. Maybe the best-looking graph would be the Audi R8's; the Porsche 911 and Mitsubishi Evo, on the other hand, appear to complete their roll a tad prematurely.

4. Lane Change/Swerve Stability

So far we've examined various targeted aspects of vehicle handling in a series of open-loop tests where we've made a steering or suspension input and then measured the car's dynamic reaction. Our lane-change test is a "closed-loop" exercise where we'll use all the controls to steer left, right, left around a 12-foot-wide obstacle filling our lane without touching cones representing other traffic.

Lane-change tests are used by vehicle-development engineers as a measure of a vehicle's stability in abrupt transient conditions. Often it's conducted as an emergency avoidance maneuver (you've heard of the Moose Test?). This protocol involves the driver entering the course at speed and then swerving to avoid a sudden obstacle, lifting off the accelerator, and possibly braking during the test as a panicked civilian might.

Another way is to negotiate the entire course like a chicane on a racetrack, as quickly as possible. Clearly this is not the way most drivers would behave if a moose suddenly loomed in the windshield, but this approach lets us use all the tricks we learn in high-performance driving school: Lift a bit to load the front tires upon entry, squeeze on the accelerator as you round the apex, countersteer as necessary, etc. We feel this approach teaches us more about the overall transient dynamics of a vehicle (and it's way more fun).

Last year we ran a typical 160-foot course that had the top-performing cars entering at above 70 mph, which can result in dramatic spinouts that traumatize the tires. To slow the test down we shortened the course by 30 feet, so don't compare this year's numbers with last year's. In fact, the official standard for the lane-change procedure (ISO 3888-1) downplays the value of the elapsed-time or average speed numbers, suggesting that the driver's subjective impressions of the vehicle's behavior are far more valuable. We agree.

5. Transitions

Our figure eight consists of two 200-foot skidpads, separated by 500 feet on center, which are traversed in a crisscrossing pattern such that you encounter left and right cornering, acceleration, and braking, and every combination in between. It's a ton more revealing than simple skidpadding.

What we're going to focus on here, though, are the transitions. Braking into cornering. Accelerating out of cornering (and from left and right directions). The graphics accompanying the figure-eight diagram are plots of each car's lateral and fore-aft g extracted from approximately three laps. These are the dreaded "g-g" graphs engineers with pocket-protectors talk about.

Basically, a car -- via its tires -- can produce roughly equal g forces in any direction, so if you drive the heck out of a car through our figure-eight course, its g-g diagram will look something like a circle except that the top (the direction of acceleration) is lopped off due to power-limitations (the grip can't be fully exploited).

Here, ideally, the dots should follow a rounded path as they migrate between the left and right, and acceleration and braking g limits (a 1g circle is shown). If the dot path looks otherwise, the car may be awkward to blend smoothly between handling and either acceleration or braking. The Nissan, BMW, and Audi appear to be strong transitioners; the Viper, Cobalt, and Evo, less so.

6. Ride Quality

We've been asked: Why do you include a measurement of ride quality in a handling story? Because it's the yang to handling's yin. The flip side of the coin. The essential trade-off. Any fool car company can build a spectacular-handling automobile by spec'ing rigid springs and humongous tires. But it's in the exquisitely engineered trade-off between ride and handling we keep finding those rare cars bejeweled with prancing horses and propeller badges popping up again and again. This isn't coincidence. It's hard work.

Of course, a few of this year's contestants offered some manner of adjustability in their suspensions, making this trade-off increasingly less strict. Press a button; have the best of both. When we encountered these features, we left the setup in max-handling mode. Button-pushing and knob-twirling in the short-shoot between your favorite corners, we'll leave it to drivers with three arms.

The results you see displayed here were acquired on a relatively short stretch of our ex-airfield site's degrading asphalt. In other words, it doesn't offer the variety of surface features we'd prefer, but nevertheless, the graphs are still telling. With a vertically oriented accelerometer on the seat cushion (in a rubber pad below the driver's tush), each car was driven steadily at 50 mph and the resulting squiggly lines were analyzed into a frequency spectrum. Moreover, the spectrum is weighted according to human tolerance for various vibration frequencies. Huh? Take a look at the graph.

That ridge at low frequencies (2-3 Hz) reflects the motion of the springs themselves. The next bump is typically the driver's seat contribution, and above that are smaller hills associated with the wheels and tire sidewall, even the engine quaking in the structure.

We started with the question of why we even do this in a handling story. The Viper and Mustang's graphs should provide a good answer.


What you've seen so far is undoubtedly the most comprehensive set of handling evaluations any magazine has ever attempted. So what have we learned, before moving our party 350 miles north to Laguna Seca Raceway? The Viper's race-car handling is counterweighted by a race-car ride. The Porsche is showing a few cracks (see step-steer). The Audi is finishing solidly everywhere. And now for road-racing ace Randy Pobst's opinion...

STAY TUNED: Part two of our Best Handling competition will run this Wednesday (Aug. 27) and the winner story will run this Friday (Aug. 29). We'll have more videos throughout the week on each car.