[Auto] BMW Z4 M40i vs. Porsche 718 Boxster S Comparison: The Sports Car Is Alive and Well

[King_of_lion]

 

There's some cause for concern over the future of the sports car. After all, in a world where cars drive themselves, what's the point of a car that's fun to drive? I'm of the opinion that in 20 years we'll look back on cars like the 2020 BMW Z4 M40i and 2019 Porsche 718 Boxster S with the same fondness we bestow on the comparatively analog sports cars that graced showrooms before the turn of the century.

But which one would I rather drive fearlessly into the autonomous future? These automakers go about the two-seat convertible sports car making different decisions at nearly every step in the process; four cylinders versus six, dual-clutch against conventional automatic, an engine up front compared to a powerplant behind your head. After considerable road and track time in both, I find these cars impressively well matched, but there's one I like a lot better.

Different Breeds, Different Hearts
These are enthusiasts' cars, which means we get to talk about the fun stuff first. The BMW and the Porsche make similar power but in different ways. This M-sport version of BMW's new roadster develops power from a 3.0-liter single-turbo inline-six sitting under its long hood, like many I-6-powered Bimmers before it.

In the opposite corner, the Boxster S approaches the matter of propulsion from an entirely different angle—one behind the driver. Between the cockpit and the rear wheels sits a 2.5-liter turbocharged, horizontally opposed four-cylinder engine. The introduction of the current-gen 718 Boxster and Cayman mark Porsche's first use of a flat-four powerplant since the days of the 912 and 914 in the late 1960s and early '70s.

What took me ten or twelve laps in the Z4 required just two or three in the Boxster. The brake pedal is softer than the BMW's and the nose not as pointy, but it's easy to correct your line and intuitive to predict the car's next move. I could get on the power much earlier, too, thanks to the mass of the engine pressing down on the rear wheels. A tidy little drift on corner exit, and I was off to the opposite lobe of the figure eight. Of the two, it was the Porsche I wanted to keep lapping.

The Real World: German Roadster Edition
As much fun as I have tearing around our figure-eight course, cones in a parking lot can only tell you so much about what it's like to own and drive a vehicle. Let's talk interiors.

This particular Z4 has bright orange seats with intricate stitching woven into the headrests. They're power-adjustable and allow the driver to tweak lumbar support and lateral bolstering, plus there's extendable thigh support for those longer of leg. The orange theme carries over to the door cards, which also feature textured metallic speaker grilles for the optional Harman Kardon audio system. Seemingly tacked-on tweeters mounted where the windshield meets the body aren't integrated so cohesively.

A 10.3-inch touchscreen infotainment setup dominates the center of the dashboard, and BMW does you the courtesy of including a one-year trial of wireless Apple CarPlay compatibility. (After the trial is up, you'll be charged $80 a year or $300 for a 20-year subscription.) As we've mentioned in previous reviews, the wireless system is finicky and we still don't like that BMW asks its customers to pay yearly for CarPlay (which not a single other automaker does). Other than that, iDrive is fairly straightforward, and most information missing from the center screen can be displayed in the Z4's fully digital instrument cluster.

Utilizing the center cupholders renders the passenger-side center armrest unusable, but they're deep and stable enough to hold my cups. A wireless charging pad is much appreciated, and there's a compartment between the seatbacks for wallets and phones and such.

The Porsche's cabin is comparatively stark. Features editor Christian Seabaugh called it "a sea of black with specs of satin metallic trim," and he's not wrong. BMW's interior is certainly more designed, but I wouldn't call it definitively better.

The seats in the Boxster move back and forth on a manual slider; the only powered control is the one that adjusts the seatback angle. The seats lack the adjustable bolstering of the BMW chairs, and although they fit my relatively narrow frame well, they won't fit everyone.

Oh, and the Porsche's cupholder game is weak. Like in the 911, two shallow claws fold out of the dashboard ahead of the passenger seat; I'd recommend sealable containers only for this one.

Porsche's infotainment screen is smaller than the Z4's, but it's better integrated into the center stack. Apple CarPlay is wired and fuss free, though interior real estate is more limited here than it is in the BMW. The center armrest has room for a single phone, but all other small cargo is relegated to hidden fold-out pockets in the door card.

While we're on the topic of cargo space, these two cars are nearly identical in terms of overall volume (9.9 cubic feet in the BMW to 9.7 in the Porsche) but—say it with me, now—they go about it in very different ways. The Boxster, being mid-engine, has two trunks: one in back behind the engine and another between the front wheels. In the Z4, there's only the one trunk out back. If you were transporting a thousand ping-pong balls, the two cars would be dead even, but because the Z4's cargo opening is wider and its cargo hold is deeper, it's much more usable in the real world.

Street Fighters
Out on the street, the differences between these two become more apparent. From the moment I pulled out of a parking space in the Boxster, I fell in love with its steering. Compared to the BMW's, the Porsche's steering felt more granular, more informative. It feels as if the Boxster's front tires are sampling the road at 120 Hz to the BMW's 60 Hz—it's that much better.

While I'm thinking about it, the Porsche's steering wheel is my idea of near perfect. It's smaller in diameter than the BMW's, has a thinner rim, and the circular airbag cover is small and well centered. The BMW tiller feels large and needlessly girthy by comparison, and it's crowded with switchgear the Porsche manages to find space for elsewhere.

There's a hint more lag in the Porsche's engine than I detected in the BMW's inline-six, though smart programming of the Boxster's seven-speed PDK dual-clutch automatic meant the Porsche was more likely to be in the proper gear with the engine on boost. Plus, if you care to shift yourself, metal paddles mounted to the steering wheel fire off shifts with alacrity, and they feel worlds better than the plastic-backed paddles in the BMW.

The eight-speed auto in the Z4 is a great iteration of a conventional automatic, though, and for driving quickly, the shift logic in Sport or Sport Plus is nearly as clever as that of Porsche's PDK. However, it does seem to slur shifts, whereas the Porsche cracks them off. (Our Vbox data shows that both transmissions shift quickly enough that there was no statistically significant interruption in acceleration, but the PDK gear changes sound and feel better to my ears and bottom.)

In terms of ride quality, neither of these two rides like a luxury sedan—a task the C8 Corvette managed on its first try. The BMW feels as if there's more rubber between you and the road, but curiously, it doesn't ride or handle as well as the Porsche on the street. Seabaugh noted that the Z4 "has a knack for finding bumps that just aren't there in the 718" and compared it to using one of those old-school "exercise" belts that just shake your belly a whole lot, promising to make it shrink.

Despite feeling more buttoned down, gut-giggle and head-toss in the Porsche weren't nearly as noticeable. We will note, however, that our tester was fitted with the optional sport suspension, which lowers the car three-quarters of an inch. If you're worried about ground clearance, I'd recommend you avoid ticking that option box—I managed to remove the Boxster's front splitter exiting a steep parking lot the first day I had it.

Lowering the top in either car is a quick and easy affair. The Porsche's roof folds in 10 seconds, the BMW's in 11, and either can erect or retract its top at up to 31 mph. The Z4 is marginally quieter and less windy with the top down, and I'm pleased to report that neither vehicle suffers from the lack of structural rigidity that can plague cars with removable roofs.

As far as driving quickly on the street, our track preferences for the Porsche carry over. Even driving at six-tenths, you can feel the Boxster's mid-engine weight distribution and its advantage in traction. It's not always easy to explore chassis dynamics on the street; a car that can do so below the limit of grip is as rare as it is satisfying.

Where the Boxster feels cohesive, planted, and adjustable when the tarmac turns twisty, the Z4 lacks composure. Seabaugh phrased it well, saying, "The front and rear feel like they're talking two separate languages." The rear is unstable on the street, and its propensity to suddenly and unpredictably lose traction is not a desirable trait in a road car. Power from the straight-six is as strong as it is linear, but the Z4 is not a car that prodded me to become a better driver.

Long Live The Roadster
Remember my concern for the sports car? I'm actually not that worried. When the horse was supplanted by the automobile as a means of transportation, did the horse go away? Of course not. Riding has become a pastime for crazed racing jockeys and hobbyists. Even when (if?) most of the cars on the road are driven by artificial intelligence rather than meat and bones, the sports car will live on no matter how much it changes.

It will become ever more important, though, that the cars driven by those who choose to do the driving themselves be involving, communicative, and celebratory of everything we love about the art of the drive.o our autonomous future? It's the Porsche.

The Porsche Boxster and BMW Z4 are strong, well-matched sports cars of the modern age, and I'm thoroughly grateful they both exist. They both have their strengths, and I couldn't fault you for buying either. But the car I'd drive fearlessly int