From the Archive: 1998 BMW M Roadster vs. Chevrolet Corvette vs. Porsche Boxster

From the March 1998 issue of Car and Driver.

In the past 27 months, five new roadsters have been introduced in the United States. The sportiest of the five are the Porsche Boxster (which went on sale in January 1997), the BMW Z3 (which beat the Boxster to the showroom by a full year), and the Chevrolet Corvette, which has been available since last September. The two other roadsters, which are not included in this comparison test, are the Mercedes SLK230, introduced in February 1996, and Mazda’s latest Miata, which should be widely available as you read this. The soft-riding, automatic-only Benz is a luxury cruiser first and is notably slower and less athletic than the three ruffians gathered here, although they challenge it nearly dollar for dollar in the market. The venerable Miata continues to be a pure roadster, but its abilities are limited by its moderately powered motor, which contributes to its affordable $20,000 price, half the price of those in the group we’ve gathered.

More Convertible Comparos

The Corvette, the Boxster, and the new more-powerful version of BMW’s Z3, called the M roadster, are all-out, go-for-broke roadsters, the performance benchmarks. We voted the Corvette and the Boxster two of our 10Best Cars for 1998 (the M roadster was still in the box). On the latest Corvette, many of the details—lack of rattles, the clean gauges, and extra storage space—are so well executed that you’d think each of these roadsters was hand-built. Porsche’s Boxster shares the new 911’s front fenders and doors and uses a 201-hp, 2.5-liter version of the watercooled flat-six engine in the new 296-hp, 3.4-liter 911 series. Do we like these cars? Does an owl hoot?

BMW will begin selling the M roadster in April. It’s powered by the company’s strongest six-cylinder engine, also found in the M3 five-seat coupe and sedan. The engine swap required a thoroughly retuned suspension and steering gear, moving the battery from the right side of the trunk to the center to make room for a dual exhaust, filling the fenders with wider tires, and installing four chunky tailpipes that exit in back.

All this extra work takes place on the same assembly line in Spartanburg, South Carolina, that builds the entire world’s supply of BMW roadsters. BMW’s famed M (for “motorsport”) department was responsible for the design and engineering and sends complete 240-hp motors from Munich, Germany, to the upstate Carolinians for installation. The lower-powered Z3 models’ engines come from Austria.

The M roadster’s in-line six-cylinder is a rev-happy motor. It fits into the small chassis the way the Great Hot Rodder in the Sky intended, increasing output from the Z3 2.8-liter’s 189 hp to 240 hp. These three roadsters cost big money—$49,235 for the Corvette, $46,385 for the Boxster, and $43,245 for the M roadster as tested. Chevrolet predicts sales of upwards of 10,000 Corvette convertibles in 1998. Porsche hopes to sell 8000 Boxsters, and BMW figures 3500 of the 20,000 Z3s it makes for 1998 will be the M-roadster model.

Exposure to the environment in our three test cars is as undiluted as in any convertible, but roadsters make no compromises for passengers behind the front seats. This selfish seating arrangement focuses the abilities of the Corvette, the Boxster, and the M roadster on pleasing the driver. Which one is the best at it?

3rd Place: Chevrolet Corvette

We’d drive the Corvette roadster about 40 percent of the time with its top down. Chalk that up to its interior spaciousness—there’s a lot of room inside for wind to swirl around and give you a chill. Although the stereo volume automatically rises with increased speed, the driveline and the exhaust make enough noise that you often need to withdraw from driving on challenging roads and just aim the car down a straight road, letting your senses cool down.

The good news is the noises are good noises: Throaty, hot-rod-­style burbling and provocative “back pops” (just quieter than a full-fledged backfire) from the exhaust make playing with the throttle fun for the ears. Beginning at about 2300 rpm under part throttle, the exhaust booms like a subwoofer.

HIGHS: Abundant power, balanced handling, and a trunk built for three.
LOWS: You must get out of the car to lower and raise the roof, and the car’s bulk makes it tough to maneuver in tiny personal spaces.
VERDICT: The fleetest of the pack, but it’s larger and feels less connected to the road than the others.

Whining about the racket is not meant to subvert the Corvette’s expression of speed: Our test car got to 60 mph in just over five seconds, which is a blink slower than the first CS Corvette roadster we tested last October. It also climbed to 167 mph with the top in place and 160 with the top down. The Corvette roadster growls through the quarter-mile in 13.5 seconds at 107 mph. (Our last hardtop was just two­-tenths of a second and 2 mph quicker.) That puts the Vette a half-second ahead of the BMW and 1.2 seconds in front of the Porsche.

The aluminum pushrod V-8 in the roadster makes 345 hp, but more notable in this field of roadsters is the engine’s 350 pound-feet of torque, which accelerates the car out of corners incredibly quickly, even at part throttle. You get a sense there’s a lot of power in reserve here. The six-speed manual transmission in our test car features a sixth gear so tall that at 70 mph the engine turns over at a mere 1550 rpm. It also features the annoying fuel-saver skip-shift feature that forces you to upshift from first to fourth gear when tooling along at part throttle at slow city speeds.

More on the 1998 Corvette

For our selfish and fuel-consumptive back-road business—conducted on some of the very tight 10Best Roads of the Southeast (C/D, January 1998)—we ignored the Corvette’s top three gears, saving them for highway cruising. The Corvette launches quickly from corner to corner on the roads that are the most fun to drive. It pulls so strongly you can sometimes avoid downshifting and still maintain as much speed.

It feels balanced on the twisty roads and also in our handling and emergency-lane-change maneuvers. “The Corvette’s chassis deserves respect—it’s utterly predictable,” said senior technical editor Don Schroeder. The Corvette has better grip on the skidpad than the Porsche or BMW, and it out­runs both of them through the emergency-lane-change contest.

So why does the car that generates the best numbers in so many categories finish third? In this test, its bulk got in the way, detracting from the complete roadster driving experience.

“The Corvette is just too big here, in reality or perception,” said technical editor Larry Webster.

We held this comparison test in South Carolina and set up a handling course on the fast and smooth Laurens proving ground owned by Michelin North America. The fast track should have favored the powerful Corvette, but Mother Nature gave the best time to the mid-­engined Porsche in the form of a traction­-limiting sprinkle of rain.

“On the track it feels big and brutish, although fast, too,” said Schroeder. “On the damp track, though, it can’t put power down without extreme oversteer—not like the Porsche, which remains neutral. You find, getting out of the other cars and into the Corvette, that it takes a while to get used to the bulk.”

Some staffers would be inclined to purchase the Corvette simply because of its sheer speed—no soft-top car that costs less can run faster. Others think the Corvette’s roomy 14-cubic-foot trunk, spacious interior, and amenities make it the best choice of the three for serving as both a weekday commuter and a weekend warrior.

But we felt that the Corvette was happier on a dry test track than it was on these very twisty back roads. As a result, when it comes to delivering the variety of sensations that only come from a topless car, the Corvette loses by a whisker to its smaller, tidier competitors.

1998 Chevrolet Corvette convertible
345-hp V-8, 6-speed manual, 3260 lb
Base/as-tested price: $45,619/$49,235
C/D TEST RESULTS
60 mph: 5.1 sec
100 mph: 11.6 sec
1/4 mile: 13.5 sec @ 107 mph
120 mph: 16.8 sec
Braking, 70­–0 mph: 172 ft
Roadholding, 300-ft-dia skidpad: 0.90 g
C/D observed fuel economy: 14 mpg

2nd Place: BMW M Roadster

We’d drive the M roadster about 60 percent of the time with its top down, for several compelling reasons: The heated seats and the reasonably draft-free cockpit mean you can drive alfresco in winter, your view out of the BMW is vast and expansive, and the top is electrically powered and lowers or rises in 10 seconds. Of the three cars in this group, this is the closest in feel to a motorcycle, and a lot of that sensation is because the doors seem low. Your left shoulder is several inches above the beltline of the driver’s door. The corner of your left eye picks up the texture of quickly moving pavement close to the car, which brings home the sense of speed you get in this roadster.

HIGHS: Drivetrain-refinement perfection, stylish upholstery wardrobe.
LOWS: The older-generation rear suspen­sion isn’t as flawless as the state-of-the-art M3 sedan’s, and you need more time to develop trust in the BMW roadster’s handling.
VERDICT: The classic definition of a roadster.

And that sense of speed is very real. The M roadster bests its M3-sedan sibling to 60 mph by a 10th of a second, getting there in 5.4 seconds. That’s approaching the acceleration of the Corvette, although the big-boy Chevy has 105 more horsepower. The quarter-mile blows by in 14 seconds flat at 100 mph, 1 mph better than the heavier M3 hardtop.

“This motor sings along at 7000 rpm with nary a vibration,” said Webster. It’s also a flexible powerplant. In the conversion to the 3.2-liter engine, BMW added a freer-breathing dual exhaust system that the M3 doesn’t have yet. Output remains at 240 hp and 236 pound-feet, but the torque curve is widened a bit. Add that to the lighter weight of the little roadster—3080 pounds compared with the M3’s 3248 pounds—and the overall effect makes the M3 feel slower. BMW admits the four exhaust pipes were added mostly for the macho look, but the next generation of the M3 (due this summer) will likely get the new exhaust system and a power increase. The bigger exhaust doesn’t mean the car is noisier, however. At full throttle with the top up, the M roadster is notably more muffled than the two other roadsters. M roadsters destined for the U.S. have less sound-deadening material inside than do European-spec M roadsters, which have been on sale overseas for a year.

The M roadster gets lower-profile front tires and wider rear tires than the Z3 2.8 we tested in our previous roadster comparison in April 1997, but it keeps the same size fenders as the Z3 2.8. Tuning the suspension for these tires required different spring rates and stiffer shock settings, but the goal of this tuning wasn’t to make the car quicker on a racetrack, but more civilized around town. It’s truly comfortable and easy to drive four-fifths of the way to its limits. Suspension bits start moving around an awful lot when the going gets quicker. Compared with the two other roadsters, the BMW exhibits the most body roll, squat, and dive. On some tight corners, you can lift the inside front wheel off the ground several inches.

“You have to be absolutely precise and smooth through the lane change, or this thing slides around and is slow. Way twitchier than the Porsche,” said Webster. “It’s the least composed of the three roadsters on the damp track,” said Schroeder. “Steering requires frequent correction, and you must compensate for weight transfers.” What he means is that lovers of the older-generation Porsche 911 who liked driving sideways can reminisce in this BMW.

The BMW’s leather seating surfaces and upholstery are beautifully color-contrasted, and the gauges get chrome bezels. Inside, this car is the most attractive of the three in this test. Outside, brake scoops replace the fog lights in front, and the rear license plate moves up from the bumper to the trunklid. We like it a lot. The Corvette costs $6000 more as tested, and it boasts a string of equipment unavailable on the BMW, such as dual climate controls, run-flat tires with integral pressure-sensor gauges, a power antenna, extra 12-volt outlets, a compact­-disc changer, memory seats, and more. Those who have come to expect all of this on a luxury-priced two-seater will miss it on the BMW.

1998 BMW M Roadster
240-hp inline-6, 5-speed manual, 3080 lb
Base/as-tested price: $43,245/$43,245
C/D TEST RESULTS
60 mph: 5.4 sec
100 mph: 13.9 sec
1/4 mile: 14.0 sec @ 100 mph
120 mph: 22.2 sec
Braking, 70­–0 mph: 172 ft
Roadholding, 300-ft-dia skidpad: 0.88 g
C/D observed fuel economy: 17 mpg

1st Place: Porsche Boxster

Not only would we take this car to the ski mountains in January with the top down, but we’d have to force ourselves to consider the downside of the latest flu before we’d put the top up, even when it rains in the summer. That means we’d want to drive this car topless about 80 percent of the time we spent in it. Maybe we’re dreaming, but just in case, we’d pack one of the Boxster’ two spacious trunks with extra jackets for the passenger. It’s not uncomfortable in wintertime (at least, a South Carolina winter) and we’re not exaggerating here: The Boxster’s high beltline means your shoulders ride level with the tops of the doors, so when the side windows are up, they block a lot of wind. Perforated panels covering the insides of the roll hoops and a plexiglass barrier between the seats also keep the air calm way down into the footwells of the car. All of this aids the heater’s ability with the top off. The Boxster is the most intimate-­feeling of these three roadsters.

HIGHS: The intuitive communication through the controls to the driver creates the magic of true partnership.
LOWS: Weak motor means it’s a dance partner not into full-tilt boogie.
VERDICT: Although many will buy this new Porsche for show, its more secret abilities blossom in private on small, intimate roads.

Successful top-down climate management is just one reason the Porsche is a good roadster. Agility, involvement, feedback, balance, sensitivity, comfort, and refined behavior in a variety of conditions are the others.

At first, the Boxster feels less powerful than the two other roadsters here. It runs the quarter-mile more than a second behind the Corvette (at 14.7 seconds). Its 7.3-second rolling-start acceleration from 5 to 60 mph feels positively sluggish after you’ve driven the two other screamers, both of which manage the task in less than six seconds.

Top speed is ungoverned at 146 mph—that’s about as fast as a V-8 Mustang. At that speed, the Boxster feels stable and doesn’t get blown around by sidewinds. Of course, the rocket Corvette goes 21 mph faster.

While you’re indulging in other full­-throttle behavior, the Porsche feels quiet and confident. The two other roadsters seem to yell and shout. The Boxster is quieter than the others when cruising with the top up, and depending on how high you hold your head, it’s a whole lot quieter when the top is down.

Roadholding ability is less than the two other roadsters’ at 0.86 g, and the Porsche was at least 3 mph slower than the others in the lane-change test. Yet the Boxster managed to run this test without leaving a mark on the asphalt. The first time through our cone-marked course, the BMW left long, wide, dark tire smears of cooked rubber—four of them. The Corvette, too, autographed the pavement and made screeching and wailing noises at its limit. The Porsche remained unruffled and unprovoked.

Out on real roads the Boxster proves its mettle. While churning the steering wheels of all three cars back-to-back on no fewer than six of the roads we divulged in January as the 10Best Roads of the Southeast, the Porsche never fell behind, despite the enormous difference in accel­eration times.

“Everything is so direct, quick, and immediate in this car—the chassis, the steering response, the roll control. It feels like the most nimble car here, which makes up for the lack of horsepower a bit,” justified Schroeder.

“I think the M roadster is more fun, but the Boxster is pretty damn fun without scaring you. It’s a tough call which is better,” concluded Webster.

It may be a tough call, but it’s one we’ve made twice now. In our comparison test last April, the Boxster earned almost exactly the same ratings that it received during this test, even though the tests occurred 2800 miles and 11 months apart. The scores for the early test’s Z3 2.8 and SLK230 were lower than those earned by this test’s Corvette and M roadster, which tell us these two latest roadsters are closer to our ideal. And our conclusion, once again, is that this Porsche is less handicapped by its moderately powered engine than you’d think. We can’t wait for the arrival of the rumored 250-hp Boxster S model this summer, with power enough for the truly impatient.

1998 Porsche Boxster
201-hp flat-6, 5-speed manual, 2900 lbs
Base/as-tested price: $40,077/$46,385
C/D TEST RESULTS
60 mph: 6.1 sec
100 mph: 16.8 sec
1/4 mile: 14.7 sec @ 94 mph
120 mph: 27.6 sec
Braking, 70­-0 mph: 164 ft
Roadholding, 300-ft-dia skidpad: 0.86 g
C/D observed fuel economy: 17 mpg

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