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The rapid-shifting, seven-speed automated manual is as quick, but no quicker than the base six-speed.
Could this be the beginning of the end for the manual transmission? BMW’s seven-speed, double-clutch automated manual transmission is now available in the M3. This gearbox shifts quicker than possible with a manual and also has a livable, smooth-shifting automatic mode.
You already know we love BMW’s latest incarnation of its marvelous M3, this time with a mammoth, 414-hp V-8. As displayed by its ferocious test numbers and three comparison-test victories, it’s simply one of the most fun and involving cars currently on sale.
But until now, all the cars we’ve driven have been equipped with a six-speed manual as we’ve waited for the brand new seven-speed, double-clutch automated manual developed with Getrag to arrive. (BMW calls it M DCT, for M Double-Clutch Transmission with Drivelogic.)
First Double-Clutch Transmission That Can Handle 9000 RPM
Available as a $2700 option on all M3 coupes, sedans, and convertibles, M DCT is the first double-clutch transmission that can handle engine speeds up to—thank-you BMW—a screaming 9000 rpm. M DCT adds about 45 pounds, according to BMW; our 3630-pound test car weighed in 30 pounds heavier than our last manual M3 coupe.
The M DCT gearbox uses two oil-cooled, wet multi-disc clutches and operates much like other transmissions of this type, such as VW/Audi’s DSG/S tronic. One clutch engages the even gears, and the other handles the odds plus reverse. Since only one clutch is engaged at any given time, the transmission anticipates and preselects the next ratio; a gear change simply requires one clutch to release while the other engages, which means the M DCT transmission can shift quicker than a manual transmission, and it drastically reduces the power interruption between gears. Overall, first gear with M DCT is actually slightly taller than in the manual, but the rest of the ratios are shorter.
The double-clutch arrangement also enables quicker and smoother shifting than in single-clutch automated manuals, such as BMW’s own SMG found in the previous M3 and the current M5 and M6. If you’ve ever driven an SMG car, you know what we’re talking about. Even with various iterations and improvements, the current seven-speed unit found in the M5 and M6 leaves large, head-bobbing gaps in power between shifts, rendering it somewhere between annoying and unusable in full-automatic mode.
As with SMG, M DCT has a staggering 11 settings—five in automatic (D mode) and six in manual (S mode)—that determine how aggressive the shifts are, with the most brutal manual setting only available with the stability control off. Settings of four or higher mean satisfying throttle blips accompany downshifts, while one through three yield nearly imperceptible gear changes. Manual shifting is accomplished via steering-wheel-mounted shift paddles (right for upshifts, left for downshifts) or the shift lever on the center console.
Thankfully Blessed With Superb Launch Control
In case you ever get your hands on an M3 equipped with M DCT, you need to know how to experience one of the best features: launch control. Omitted from U.S. versions of the M5 and M6, launch control is thankfully now included in the M3.
With stability control switched off and the transmission in the most aggressive setting, simply push and hold the shift lever forward and a checkered flag appears in the dash display to let you know you’re in launch-control mode. At that point just flat-foot the throttle and the revs rise and hold. Using the cruise control stalk, that rpm hold point can be adjusted between 4600 and 6100 rpm to tailor the launch to the particular surface. With your foot still flat on the floor, let go of the shift lever and it executes a perfect, clutch-dump launch every time. In this mode it also upshifts automatically through the first five gears.
One caveat: M DCT won’t allow multiple, successive launches in this manner. During our runs, it required three- to five-mile cool-down runs before allowing another attempt.
But Is it Quicker?
After scouring the test results for some useful conclusion, the answer is “not really.” The M DCT car hit 60 mph in 4.3 seconds, cleared the quarter-mile in 12.7 at 113 mph, and achieved 150 mph in 26 seconds flat. Compare that to the six-speed manual’s numbers of 4.3, 12.8 at 113, and 24.3, respectively. If you zoom in even closer and look at each 10-mph increment, the two cars tradeoff which one is quicker until 120 mph when the manual starts pulling away.
Still No Replacement for the Manual
The M DCT gearbox is no doubt a technical marvel, but we don’t yet prefer it to a traditional manual.
First off, the throttle response from a standstill is annoyingly lazy. Most times we found ourselves pushing the pedal about halfway down just to get a reasonable response. When attempting to merge into busy traffic, we often used so much pedal as to hit the kickdown switch on the floorboard to get the M3 moving. And then once the clutch finally engages, you get too much acceleration and often, wheelspin. This slow clutch engagement is disconcerting and we all agree that it’s far quicker and easier to get a swift, predictable step-off in the manual version.
Second, when accelerating hard, there’s a fair amount of lag between the time you pull the shift paddle and when it actually upshifts. On an aggressive shift from first to second, you have to shift around 7200 rpm—nearly 1000 rpm early—to get it to change gears before the engine hits the 8400-rpm limiter. We never had this issue with SMG in the M5 and M6, and after hitting the limiter multiple times, we yearned for the manual. And when it finally does shift, it often slams into gear so violently as to upset the car.
We found the downshifts to be quicker and more acceptable, although in automatic mode, wide-open-throttle, two-lane passing maneuvers at 55–60 mph (a seven-to-two downshift) seemed no quicker than in a traditional automatic.
However, the taller seventh gear does allow the engine to run about 200 rpm lower than sixth gear in the manual, which could marginally improve real-world highway fuel-economy numbers. In Europe, the double-clutch M3 gets slightly better fuel-economy figures but U.S. EPA ratings remain at 14 mpg city, 20 mpg highway for either transmission. However, automatics generally get worse fuel economy, so parity isn’t necessarily a bad thing. We saw 20–21 mpg on a relatively flat, couple-hour highway slog.
For sure, the automatic mode—other than the lazy clutch engagement on step-off—is much improved over the SMG and now perfectly acceptable. Keep it in one of the less aggressive settings and the shifts are so smooth you might miss them unless you’re paying close attention. And, unfortunately, there’s a strong demand for automatics in high-performance sports cars. But—other than the launch control feature—we think it’s far easier and more satisfying to exploit the M3’s excellent dynamics with a traditional manual, which was not necessarily what we expected.
VEHICLE TYPE: front-engine, rear-wheel-drive, 4-passenger, 2-door coupe
PRICE AS TESTED: $69,425 (base price: $61,325)
ENGINE TYPE: DOHC 32-valve V-8, aluminum block and heads, port fuel injection
Displacement: 244 cu in, 3999cc
Power (SAE net): 414 bhp @ 8300 rpm
Torque (SAE net): 295 lb-ft @ 3900 rpm
TRANSMISSION: 7-speed manual with automated shifting and clutch
DIMENSIONS:
Wheelbase: 108.7 in Length: 181.8 in Width: 71.0 in Height: 55.8 in Curb weight: 3630 lb
C/D TEST RESULTS:
Zero to 60 mph: 4.3 sec
Zero to 100 mph: 9.9 sec
Zero to 150 mph: 26.0 sec
Street start, 5–60 mph: 4.9 sec
Standing ¼-mile: 12.7 sec @ 113 mph
Top speed (governor limited): 161 mph
Braking, 70–0 mph: 147 ft
Roadholding, 300-ft-dia skidpad: 0.96 g
FUEL ECONOMY:
EPA city/highway driving: 14/20 mpg
2008 BMW M3 With M DCT Double Clutch Transmission - Short Take Road Test/BMW Performance/M Power/High Performance/Hot Lists/Reviews/Car and Driver - Car And Driver
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