If there's one thing this fourth-generation ND Mazda MX-5 got wrong—even the sportier Club version—it's what we call flop. Drive it hard into a corner, and the otherwise well-behaved fingertip-controlled roadster uses up all of its suspension travel, especially in the rear, and hits its bump stops abruptly. If electronic stability control is disabled, what happens next depends on driver experience and skill. This is one of the primary reasons a 2016 MX-5 only garnered a third-place finish in our annual Best Driver's Car contest. What the MX-5 needs is added roll stiffness. Along comes a slightly heavier fastback body style for 2017, and Mazda was forced to address the flop.

Flop Reduction and Reaction

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What they did was change one of the suspension bushings and softened the bump stop so when all the suspension travel is used up, the transition to flop-induced oversteer is less abrupt. This means the RF is easier to control on the limit of grip and easier to predict and balance when you need it most. During the filming of an upcoming episode of Head 2 Head, senior features editor Jason Cammisa, who likes cars to drift predictably, said: "It still leans a ton, but it's far better controlled, to the point where you're not working around it, and you can always trust the rear end." Part of this is owed to the manual transmission's standard limited-slip differential, but the other is in the suspension bits. "Once on the bump stops in corners, the rear now has actual damping left—so the rear end doesn't bounce around and get knocked sideways by mid-corner bumps," Cammisa said. However, after lapping the Streets of Willow racetrack, Motor Trend's hot shoe, Randy Pobst, disagreed. "Bump stops should not be an obvious part of the suspension equation; witness the Toyota 86," he said. "They're invisible. There should be no need to slow the roll with your hands when proper damping would do it for us. There's still too much body roll [in the MX-5 RF], but there's still great balance."

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In Randy's hands on the 1.6-mile Streets of Willow track, the Toyota and Mazda were almost in a dead heat. The 86 pipped the MX-5 RF by little more than 0.1 second: the 2017 Toyota 86 at 1:30.26 and the 2017 Mazda MX-5 RF with a 1:30.39 best. Considering the RF gives up 50 horsepower to the 86, that's a pretty close race, and it demonstrated the dynamic excellence the MX-5 embodies.

Performance Differences

Depending on options, the weight difference between an MX-5 roadster and retractable fastback (RF) is a little over 100 pounds. The lightest MX-5 6MT Club roadster we've tested at 2,296 pounds is 124 pounds lighter than the MX-5 RF 6MT Club we tested. Both had the Brembo/BBS option, but that's all. It boils down to the RF hauling around 0.8 pound more for each one of the 155 horses the identical 2.0-liter four-cylinder engines can provide. That doesn't sound like much, so how does this added weight affect their performances? Almost imperceptibly, and you'd need an experienced test driver and a data logger to measure it. Luckily, we've got a few of those lying around. Initially, the two cars are door handle to door handle, up to about 25 mph. The RF's weight begins to cost time by 30 mph, where it consumes 2.0 seconds to the roadster's 1.8 seconds. After two upshifts, 60 mph arrives in 5.8 seconds for the roadster and 6.4 seconds for the RF. Physics takes over by the end of the quarter mile, with the roadster crossing the line in 14.5 seconds at 94.2 mph and the RF in 14.9 seconds at 92.4 mph. Fresher tires likely helped the RF stop 2 feet shorter from 60 mph, at 109 feet, but they didn't help on the skidpad, where the roadster averaged 0.97 g to the RF's 0.91 g. Putting all the dynamics together on our figure-eight course, the roadster produced a 25.2-second lap to the RF's 25.9 seconds. Mere fractions of a second separate the two, and that's success in our book.

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Real-World Driving

The front portion of the MX-5 RF's sound-insulated retractable panel is made of aluminum, the middle is steel, and the rear buttresses are SMC (sheet-molded compound) or plastic. The roof is not load bearing, so the roll hoops from the roadster remain behind both seats. With the press of a button, it takes about 13 seconds to either stow or replace the roof panel beneath the buttress at speeds up to 6 mph. We were told that relatively low maximum speed was determined to eliminate the possibility of long hair being swept into the mechanicals. However, unlike some other retractable hard tops, there's no loss of trunk access or space compared to the roadster because either top effectively stows in the same space behind the seats—a pretty neat feat considering electric motors/actuators and such.

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With the RF's top in place, the sound isolation is predictably far superior to the roadster's soft top. Even at highway speeds, it's easy to have a conversation without raising one's voice even with the audio system on. With the panel stowed, however, we suspect the wind noise is actually greater in the RF. We don't have data to validate this impression, but the buffeting at the rear edges of the side glass (where they meet the bulkhead) that begins to occur at 45 mph is rather loud. We lowered the windows, and it grew worse. We tried windows partially down, and the din was somewhere in between. We're told that there's a happy medium with one window all the way down and the other partially down, but we didn't crack that code on our drive.

Another subtle difference between the RF and the roadster was Mazda's recalibrated steering for reduced on-center friction and slightly higher effort elsewhere. The same 15.5:1 overall steering ratio is used in both, but we think the RF's calibration perfectly suits the character of the car to feel a little pointier initially but also a bit more substantial in the corners. Despite the weight difference and the RF carrying about 2 percent more of it at the rear, the RF feels supremely neutral and poised—more so than the current soft top. "Cornering balance is bordering on perfect," Cammisa said. "You never have to manage the front tires, not on track and certainly not on the street." Ride compliance is obviously a trait Mazda values. Otherwise it would have added beefier springs or more anti-roll bar to net handling gains. An old race car driver once said: "The trick to making a car handle well is not to make it as stiff as possible and get away with it. It's to make it as soft as possible and still get away with it." Apparently the folks at Mazda have the same mantra.

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As a whole, the RF essentially maintains the lighter roadster's performance, but it does so with more civility and confidence. This made us ask Mazda why it don't simply make an MX-5 coupe. The rehearsed answer went something like: "That's a decision made officially in Japan, and we can tell you that it will never happen." Whether you like the looks of the fastback over the soft top is a matter of taste, but how it drives will continue to inspire what Mazda calls the MX-5's jinba ittai core spirit. Literally translated, it means "rider and horse; one body," and that's the part that translates into one of the best driving experiences money can buy. Although the car we tested was of a RF Club 6M with the Brembo/BBS package, we recently drove 2017 RF Grand Touring 6M, and subjectively it felt only slightly softer but no less jinba ittai to us. We'd have to run it out to the track to make any objective conclusions, but we appreciated the heated leather seats and SD card navigation system.

The Lineup

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On sale now, the 2017 Mazda MX-5 RF forgoes the softtop's basic Sport model and comes in just two flavors. Starting with the six-speed manual transmission, the Club ($32,390) and Grand Touring ($33,455) feature a limited-slip differential, Bilstein dampers, and a shock-tower brace up front. Adding a six-speed automatic transmission to either one (plus $730 on Club, $1,205 on GT) removes the LSD and above suspension hardware but adds keyless entry. In broad strokes, the Club features LED head/daytime lights, manual climate control, a knob-controlled infotainment system with a 7.0-inch color touchscreen, Bose nine-speaker audio, HD and satellite radio, a CD player, Bluetooth phone/audio, two USB ports, and an auxiliary audio jack. Standard safety includes blind-spot monitoring and rear cross-traffic alert—features that were once only available on the Grand Touring. A Brembo (front) brake and forged BBS wheel package ($3,400) is available on the Club 6MT, which also includes an aero kit and keyless entry.

The Grand Touring automatic adds automatic climate control/headlights/wipers, heated, auto-dimming mirrors, heated leather seats, and navigation. Safety is enhanced on the GT with an alarm system, auto high-beams with road following, and a lane departure warning. There are also two U.S.-exclusive Launch Editions (limited to 1,000) with the manual ($34,685) and automatic ($35,760), which are essentially Grand Touring models with a black top, Nappa leather, and gray metallic paint.

2017 Mazda MX-5 Miata (RF Club 6MT) BASE PRICE $32,390 PRICE AS TESTED $35,790 VEHICLE LAYOUT Front-engine, RWD, 2-pass, 2-door convertible ENGINE 2.0L/155-hp/148-lb-ft DOHC 16-valve I-4 TRANSMISSION 6-speed manual CURB WEIGHT (F/R DIST) 2,420 lb (50/50%) WHEELBASE 90.9 in LENGTH x WIDTH x HEIGHT 154.1 x 68.3 x 49.0 in 0-60 MPH 6.4 sec QUARTER MILE 14.9 sec @ 92.4 mph BRAKING, 60-0 MPH 109 ft LATERAL ACCELERATION 0.91 g (avg) MT FIGURE EIGHT 25.9 sec @ 0.71 g (avg) EPA CITY/HWY/COMB FUEL ECON 26/33/29 mpg ENERGY CONS, CITY/HWY 130/102 kW-hrs/100 miles CO2 EMISSIONS, COMB 0.67 lb/mile