Written by Per Schroeder
From the Feb. 2006 issue
Posted in Shop Work
There’s no doubt that the new Mazda MX-5 Miata and Pontiac Solstice are attractive cars, but appearance doesn’t mean much when you’ve got a helmet strapped on and are hurtling toward an apex at warp speed. The true sports car is not about being sporty looking—it’s about sports. Motorsports with a capital “M.” That’s where adrenaline and gasoline mix into a concoction of which only a gearhead would willingly partake.
As gearheads, we couldn’t think of anything better than taking two of these newest and most anticipated roadsters and beating the snot out of them. We’ve all read the hype on the MX-5 and the Solstice, but are they really cut out for true high-performance use?
Testing the cars at the limit would show us which, if either, was the heir to the sports car dynasty and not just a pretender to the throne. Which car would stand up to the use and abuse that an autocross or track day can dish out? How would those suspensions fare when push came to shove?
We also wanted to see how the new cars would stack up against autocross’s current lightweight roadster benchmark, the Mazda Miata. The Miata has been the poster child for autocross cars since its introduction for the 1990 model year. Its low price and fun-to-drive quotient are strong arguments that many enthusiasts have found hard to resist.
A redesign for 1999 did little to rain on the Miata enthusiast’s parade, and the car has continued to rule the roost. In fact, the second-generation Miata has become the car to have in SCCA C Stock autocross competition. Looking back, our July/August 1998 issue predicted that the 1999 Miata would unseat the first-generation Miata. That statement has since been proved true.
Our plan was simple: Bring a 2006 Mazda MX-5 and a 2006 Pontiac Solstice to The Tire Rack’s headquarters for a few days of hardcore testing. Exercising them on a closed track would allow us to explore the limits—and go well beyond them—in an effort to see how the cars would perform in amateur motorsports.
While the two new players haven’t been classed yet by the SCCA, we’re betting that they’ll have to face off against the most recent Miata in the C Stock class for autocross competition.
To make things more equitable and even more interesting, we fitted all of the cars with sticky race rubber: Hoosier’s new A3S05 tires. Original equipment tires typically just aren’t meant for track use, and putting all of our test vehicles on the same rubber would make this a fair comparison. It would also yield better feedback as to how the cars would react in a competition environment. Race compound tires can highlight strengths or weaknesses that aren’t readily apparent with the lower-grip tires that come on practically all street-going cars.
We also brought along a benchmark for the test, again calling Chris Harvey’s 1999 Miata into service. This car is thoroughly prepared for the SCCA’s C Stock Solo 2 class and posted the top two times during the second day of competition at the most recent Tire Rack Solo National Championships. (A damp first day prevented Chris and his co-driver, Joe Tharpe, from posting a strong finishing position.)
Chris’s Miata has benefited from six years of development, and it has been fortified with a Racing Beat 11/8-inch front anti-roll bar, revalved Koni shocks and a pretty serious competition alignment. Chris runs 1.2 degrees of negative camber in the front and one degree in the rear. Toe is adjusted to zero in the front and 1/8-inch toe-in for the drive wheels.
It would be unfair to pit the new rivals against the incumbent without some rudimentary tuning, so before we began our testing, the two new kids on the block were taken to nearby Veldman’s Service Center of South Bend, Ind., for a competition alignment. This typically entails dialing in as much negative camber as the factory tolerances will allow and adjusting the front and rear toe to near zero—or even a little bit of toe-out—to get rid of the numbness that the factory-specified toe-in will cause.
The all-new MX-5, like the Miata before it, has some room for adjustments in its double-wishbone suspension. Unfortunately, we could not quite get a full degree of negative camber up front. (The maximum camber setting yielded 5.80 degrees of caster, by the way.) The rear suspension was adjusted to 1.5 degrees of negative camber, and zero toe was dialed in for all four corners.
The Solstice’s front suspension allowed for an impressive 2.0 degrees of negative camber with more than 6.2 degrees of caster. We set the rear of the Pontiac at 1.5 degrees of negative camber and, once again, used zero toe at all four wheels.
All three cars were then rolled into The Tire Rack’s garage, and fresh autocross-compound Hoosier A3S05 tires were mounted up. The 1999 Miata was fitted with 225/45R15 tires on its lightweight 15x6-inch SSR wheels. The 225/45R15 Hoosier is an excellent size tire for the Miata, and it’s one reason why Chris and his co-driver were so fast in Topeka.
The 2006 Mazda MX-5 was fitted with 225/45R17 Hoosiers on its factory 17x7-inch wheels. (Those stock wheels are nice and lightweight at a hair over 17 pounds apiece.) The rear tires were a very tight fit, however, as the inner fender has a large lip that protrudes almost an inch into the fender well. This won’t be a problem for those who are in classes that allow for fender lip rolling, but this can really limit the width of the rear tires for stock-class autocross.
The Pontiac Solstice was blessed with gigantic 18x8-inch alloy wheels. That blessing became a curse once we had to heft one onto a scale: They weigh a stout 23.8 pounds each. On the plus side, a set of 245/35R18 Hoosiers perfectly fits these attractive wheels and provides a large and grippy footprint.
We ran the same test course at The Tire Rack that we used for our latest tire tests. This 40-second course is a combination of sweepers, offsets and diabolical braking zones that can really highlight differences in a vehicle’s dynamic performance. Each car was run and weighed with as little fuel as possible.
The driving duties were performed by GRM’s Per Schroeder and two drivers from The Tire Rack, Chris Harvey and Woody Rogers. Woody and Chris admit to having more than a thousand laps under their belts on this track, so they needed little time to acclimate themselves to it for our testing.
Each of our drivers took five laps per car. Woody ran first, followed by Chris and then Per. Tire pressures were checked after each run, and tire temperatures were monitored for overheating. The tires were cooled to prevent overheating and loss of grip. After the dust had settled, times and pylon counts were tallied and the means were calculated.
2006 Mazda MX-5 Grand Touring
We’ll be blunt: The 2006 Mazda MX-5 is going to make a lot of money for aftermarket suspension tuners. Our test car had the optional sport Suspension Package, but the car was still way too soft with what appeared to be very little rebound damping from its Bilstein shock absorbers.
That suspension—and the suspension alone—let this car down lap after lap. The MX-5 had the slowest average lap times of the three cars at 40.215 seconds. Its single quick lap, a 39.177-second run, was attributed to “dumb luck” on Woody’s part, as he said himself. Every other time recorded by the car was at least half a second slower.
The lack of body control kills the driving fun of this car once it exceeds nine-tenths of the limit. Chris put it succinctly: “Soft springs, soft anti-roll bars and soft shocks. Ugh.” Chris also mentioned that the steering has an artificial feel when moving through fast transitions, almost as if the gear is making the response harder when the driver needs to move the wheel quickly.
Woody noticed an uncertain feel when driving into and through the offsets across the top of the course. “It wasn’t easy to estimate how fast the car can go through the element,” he said. “It was easy to under- or overdrive this section.”
The Mazda had the least amount of grip from its front tires—remember how little negative camber we could achieve?—and as a result the drivers were always waiting for the front tires to “hook up” before they could use the extra power. Chris theorized that the MX-5’s limited negative camber, tall ride height and lack of roll control all contributed to the problem. “Dear Santa, all I want for Christmas is for the suspension engineers at Mazda to rethink their spring rates and lengths,” Per joked.
Not that the rear of the car liked to stay put, either. All of our drivers noted that the Mazda would transition to oversteer when the steering wheel was muscled. Smooth hands and patience were required to find the quick lap times. Unfortunately, given how the steering feel changed during the faster slalom portions, this became a tall order. Backing off the gas in the curves also led to lift-throttle oversteer at the limit, with all of this happening too quickly to be useful as a car placement tool.
The “new Miata,” as we kept calling it, does have a few strong points. Chris noted that the 2.0-liter engine was willing and smooth; its flexible power pulls it to the rev-limiter. Unfortunately, that rev-limiter came on way too soon, just as we were starting to enjoy the engine’s 170 horsepower. The gearing of the six-speed transmission is a little low for autocross use, and we found the engine ding-ding-ding-dinging at the end of even short straights.
That short gearing and strong engine did combine to do well in one test, as the MX-5 turned the quickest time in our 20-to-50 mph test. The car’s strength in second gear was impressive.
The brakes are also very strong, with great pedal feel. “Monster brakes feel like you’ve thrown out the anchor,” Woody said. Unlike the early Miata, the MX-5’s anti-lock brakes made it easy to get the car slowed down in the braking zones with little fuss. Unfortunately, as Woody noted, the car also pitches forward alarmingly under hard braking. Again, the soft suspension keeps the MX-5 from success.
Given all of its weak points, the MX-5 could respond well to some intelligent tuning. An aftermarket front anti-roll bar for the Mazda RX-8 will bolt onto the MX-5 without modification—in fact, Racing Beat already has a 1.25-inch bar that’s hollow for light weight. Stronger shock absorbers with more bump and a lot more rebound would also be helpful. We’re not convinced that these would be enough to tame the MX-5’s bad habits, but they’d certainly help.
Going beyond the scope of stock-class preparation, the MX-5 could certainly stand to be lowered at least an inch, which would in turn yield additional camber that would further improve matters. The stock spring rates are willowy-soft, so a set of coil-overs would make for a much more stable and rewarding platform.
The MX-5 that we tested had the Grand Touring package, which includes leather seats and a cloth top. Including the car’s optional Suspension Package—which adds the sport-tuned suspension and limited-slip differential—our MX-5 stickered for $25,495 after delivery. A straight Sport package MX-5, which would still include all of the performance bits but would lose the leather and cloth top, would be about $1500 less.
2006 Pontiac Solstice
From the first turn of the Solstice’s steering wheel, we were pretty certain that the results of this test were going to be surprising. The Pontiac Solstice has the suspension to back up its sports car looks. Sorry to say to the car’s detractors—who are, admittedly, fairly numerous given the car’s polarizing styling and domestic heritage—but this is more of a contender than a pretender.
The Solstice cornered with little body roll, and the shocks felt largely up to the task of performance driving. Only the Ecotec engine disappointed, as it felt a little thrashy and anemic; but that was only in comparison to the MX-5’s jewel of a mill. Despite the Solstice’s parts bin engineering, it is a staggering achievement from the same folks who brought us the Aztec.
While we’re often heard saying that low weight is the Holy Grail of performance, the rather portly Solstice feels very light on its feet. It transitions, corners and brakes well, despite weighing some 350 pounds more than the MX-5 and nearly 600 more than the Miata.
The Solstice is also the easiest car of the bunch to drive quickly. Within just one or two laps, our drivers were nearly equaling the times of the 1999 Miata. Incredibly, Woody’s second lap in the car was the time to beat at 38.898 seconds, just 0.097 behind Chris’s fast time in his own well-developed 1999 Miata. The average time for the Solstice was equally impressive, at just two-tenths of a second behind the Miata.
Chris found that the Solstice had excellent body control. “Flat cornering and controlled pitch and dive make the car very easy to come to terms with,” he said. This is helped by the Solstice’s capability for large amounts of front camber adjustment, and the 8-inch-wide wheels provide excellent turn-in and corner entry grip. We could have dialed in even more negative camber if we wanted, as 3 degrees were available. That’s an impressive amount of adjustment.
“This car is easy to place, corner after corner, lap after lap,” Woody said. “I could quickly settle into a rhythm and maximize the car’s performance. It was locked in on the skidpad portion of the course.”
The Pontiac’s balanced chassis and great brakes challenge the driver to be more aggressive. Our car had the ABS brakes, which is a $400 option and well worth the extra cost.
Oddly enough, we found that one aspect of the car that’s a negative in daily driving was actually helpful on track. Chris noted that the tight quarters in the cockpit allowed him to easily brace himself with his knees.
The Solstice wasn’t without its weak points on track, however. All of the drivers commented that limited visibility hindered car placement. It took a few runs for the drivers to find the edges of the car and thus a few cones met their maker. The car’s weight and width do limit its ability to slalom quickly, but not overly so.
The Ecotec engine wasn’t the Solstice’s high point. It was found to be quite noisy at higher engine speeds, and its thrashiness was even noted during our hot laps. The car’s 2778 pounds sapped the 177-horsepower engine of much of its strength. The Ecotec did win the torque award, putting out 166 lb.-ft. of torque from its 2.4 liters.
Our test car lacked a limited-slip differential (it was probably the only free Solstice in the press fleet at the time), which prevented some of that engine power from getting to the pavement. “I got inside wheelspin accelerating into the slalom, and after the last offset to the 180,” Woody noted. We couldn’t tell for certain if it was greatly affecting our lap times, but the absence of a limited-slip was noticeable. Since this is only a $195 option, it’s an obvious upgrade for the performance driver.
A Solstice equipped with ABS and a limited-slip should sticker at just $21,165 with destination charge. Even our fairly loaded test car—leather, cruise, driver info center, air conditioning, power locks, polished wheels, XM Satellite Radio and much more—carried a reasonable MSRP of only $24,505 after destination.
That amazing price is somewhat muddied by dealerships charging markups due to high demand for the car. We’ve heard reports of Solstices selling for north of $30,000. Hopefully the fever will subside enough that enthusiasts can find them before they’re all snatched up by poseurs who just want the “it” car.
As for tuning potential, one major hurdle for the Solstice is a lack of aftermarket tuners that specialize in small GM cars, let alone a completely new model. Improvements will probably be seen first from shock companies like Koni. While the O.E. Bilsteins are a noble effort, they lack the rebound control that a hardcore autocrosser needs. The aftermarket wheel companies can probably also help the car’s performance with some lightweight offerings.
We’d suggest a stiffer front anti-roll bar as a good next step after the lighter wheels. The Solstice looks like it could also drop some weight with an aftermarket exhaust, ideally one that would give the Ecotec a more pleasant note.
1999 Mazda Miata
The 1999 Miata is our benchmark for a reason: It’s one of the fastest ways to get around an autocross course without taking out a second mortgage. Our drivers posted their fastest times in the Miata, with Chris’s best being a 38.801-second run. The Miata also had the fastest overall average at 39.364.
The lightweight and small Miata was simply a joy to throw into slaloms and chuck into sweepers. This is a car that, given enough driver confidence, can pull off times that would shame a Porsche or Corvette.
Tipping the scales at just 2197 pounds, the Miata feels even lighter through slaloms. The trick is to throw the car just the right amount, without overdoing it. Familiarity with the Miata is paramount for quick laps.
After a few laps, Woody got the hang of the car. “It requires some work to make it go fast,” he said. “I’ve really got to concentrate. More familiarity would bring more confidence and more speed. You don’t want to anger the car into a spin.”
Despite the Miata’s small footprint and relatively limited amount of negative camber, it generates a lot of grip. Credit the light curb weight and low center of gravity for this. Grip is secondary to just how nimble and tossable the Miata is. Woody mentioned that the car felt like a go-kart in comparison to our other test candidates.
Where the MX-5 has a strong engine on its resumé, the Miata’s engine is one of its weak points. Chris mentioned that his car, despite a favorable horsepower-to-weight ratio, really needs an additional 20 lb.-ft. of torque. Even with its low curb weight and 140 horsepower, the Miata felt like the weakest of the bunch when accelerating out of the 180-degree turn onto the skidpad. Backing this up, the Miata was the slowest car in our second-gear acceleration test from 20 to 50 mph.
The car’s brakes can also make high-speed driving difficult. The lack of ABS and a good amount of negative camber caused the front tires to lock up very easily, especially when the inside was unloaded on corner entry. Several runs were overcooked by drivers who were simply not able to slow down the Miata enough. At the end of the day, our right-front tire had several flat spots from premature lockup.
The Miata may have posted the fastest times, but don’t forget that our test vehicle has also received some six years of development. Once the other cars, especially the Solstice, have been tweaked a bit, the gap should shrink—or maybe even reverse directions.
So, after driving all three cars, which one would we buy if it were our money on the table? Without copping out, we’d have to say, “well, it depends.”
If the goal was an SCCA C Stock national championship in 2006, we’d order a Solstice and pray that our local dealership didn’t try to rape us with additional markup. We can see the Solstice, with just a little tuning, becoming the dominant car for stock class autocross. It’s just such a willing partner for on-track shenanigans.
If the goal was to have a fun project car for track days and autocrosses with an eye toward modifications and improvements, the hands-down choice is the MX-5. It’s simply the coolest car of the lot.
In the “duh, no comparison” column, our recommendation for budget-minded racers is, of course, the Miata. You can pick up a first- or second-generation Miata pretty cheaply and have a blast in a number of different classes and venues. It’s simply the most fun car to drive, whether you’re going to the store or taking hot laps.
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