On Notice: Goodbye, ZR1 and Everybody Else
Our resident hot shoe Randy Pobst idles back into the pits in the Z06. It’s turned into a humid, 85-degree afternoon here at Road Atlanta — we’d spent the morning in the garages waiting out a rainstorm — and the white car with the black wheels and black wings looks purposeful against the tarmac and bright green trees. Pobst gets out, and the small group of Chevrolet engineers approaches, eager to hear his thoughts. Impatient for our data acquisition hardware’s results, they’d been timing his laps on their phones: 1:30.17, 1:30.21, 1:30.67. One of Pobst’s thoughts: “The power felt great. Honestly, I want another hundred more. It’s stable enough. You don’t feel threatened.”
It’s a strange comment when you consider the last-generation ZR1, whose powerband made you keenly aware of its awesome potential. During our 2009 Best Driver’s Car test at Mazda Raceway Laguna Seca, Pobst said, “It’s one of the very few cars I’ve ever driven here where I didn’t want to keep my foot down over Turn 1.” This new Z06 not only generates more power, making it the most powerful vehicle General Motors has ever produced, but this white one Pobst just exited also has an automatic and a removable roof. It’s also available as a convertible. And Pobst wants more power. The world’s gone mad.
Tadge Juechter, the chief engineer of Corvette, is in the group. Earlier he told us the automatic gearbox and roofless construction were part of the goal, but supplanting the ZR1 wasn’t. They’d started with a high-revving, big-displacement “spinner” V-8 like the 7.0-liter in the last Z06, but they couldn’t hit emissions targets. So they hit reset and started again with a supercharger. It’s a compact Eaton TVS Roots-type unit, smaller in displacement and more compact than the blower atop the ZR1’s mill. Versus that engine, at 650 hp and 650 lb-ft of torque, the Z06’s LT4 V-8 makes more power (12 hp and 46 lb-ft of torque), weighs 33 pounds less, and employs direct injection and cylinder deactivation.
Advancements in aluminum construction permitted a stronger chassis that doesn’t suffer a performance penalty when you remove the roof. It is heavier, though. The Z06 we tested had a Z07 package ($7,995 for carbon-ceramic brakes, third-stage aero package, and gumball tires) and a seven-speed manual. At 3,533 pounds on our scales, it has gained 189 pounds versus the last ZR1 we tested.
That new eight-speed automatic must add more, right? Nope, it appears to be the product of the Have Your Cake and Eat It Department. Chevy engineers looked into twin-clutch gearboxes but couldn’t find one that withstood the torque output, fit the packaging constraints, or met weight targets. They built an automatic that would, and the remarkably compact result weighs only 8 pounds more than the manual. With faster and more aggressive shifts, a wider ratio spread, and a tall eighth gear (1,200 rpm at 60 mph), it benefits both performance and fuel economy. It also helps produce an utterly satisfying bark on full throttle upshifts.
The Z06 appears to be the product of the Have Your Cake and Eat It Department.
Leave the transmission to its own devices in Track mode, and it makes impeccable gear selections, even finding speed by shifting in places you normally wouldn’t. Road Atlanta’s Turn 3 at race speed puts two wheels in the air. You want to downshift for the next corner, but this isn’t the time to take one hand off the wheel. “Consistently I’d go over the bump,” Pobst said. “The landing is sweet, so sweet — and I’d go to the power and say ‘Whoa!’ I was not expecting to be in that low of a gear, but it put the power to the ground.” The automatic makes the shift in the air.
While the automatic makes the Z06 the faster car, limited vehicle availability meant we could only run performance tests on a manual. As with the last-gen ZR1, launch control is more consistent but ultimately slower. Exercise some patience, find the right amount of tire chatter, and you’ll reach 60 mph in 3.2 seconds and the quarter mile in 11.3 seconds at 126.2 mph. Peak stopping performance — 91 feet from 60 mph — remains as absurdly low as the last ZR1’s, and all stops during this test stayed under 100 feet.
Would it be shocking to call the Z06’s lateral capabilities more impressive than its acceleration? Its 22.5-second lap on the figure eight is the second-fastest production car we’ve tested behind the Porsche 918’s 22.2 seconds; the Z06’s 1.16 average lateral g is the highest we’ve seen from anything that wasn’t a race car. Credit the Michelin Pilot Sport Cup 2 tires included in the Z07 package. Their bare shoulders have small “vestigial” tread marks, per Juechter, and their combined section width totals 4.1 feet. With my right knee and elbow against the tunnel, my left against the door, it felt like driving a Tilt-A-Whirl.
The section between Road Atlanta’s Turn 3 and Turn 5, a rapid switchback of esses, exhibits just how much cornering force is at the Z06’s disposal. The data from Pobst’s lap show six alternating 1.0-plus g moments in the span of 14 seconds. Although our test cars had the optional bucket seats, they weren’t enough. “The seat is actually really supportive for a street seat,” Pobst said. “But this is not doing street things out there. I need belts or something to hold me in place.”
It may sound like the Z06 follows the “No Duh” approach to fast car development: Low weight and ludicrous quantities of power and tire. But there’s sophistication between those parts. Fast-reacting magnetorheological fluid-filled shocks provide excellent control, especially when you have two wheels in the air. An electronically controlled locking differential biases power where and when it’s needed, even helping to prevent the tank slap-like behavior you get when you don’t come out of a powerslide perfectly. Chevrolet’s fantastic Performance Traction Management allows you to learn and explore the car’s limits with less fear. These components make the Z06 controlled, compliant, and easy to approach.
Another neat trick: A Performance Data Recorder stores images and data from a front-mounted camera, vehicle sensors, and a 5-Hz GPS sensor to a video file on an SD card. The YouTube-ready video file shows throttle and brake position, g readouts, and so on. Provided software incorporates top-view satellite images to show your placement lap by lap. Owners can even use the system to discourage would-be hot-shoe valets.
The price is bewildering, as you’d need to spend nearly $1 million elsewhere to reach Z06 performance.
But for the technical prowess, you might be surprised to learn that the Z06 eschews active aero for a far simpler solution: three aero packages in increasing aggressiveness. The first is the Z06’s standard equipment, and the second adds a front splitter with end plates, rocker panel extensions, and a spoiler—all of it in carbon fiber, and all of it fixed. The third stage uses the second-stage components as mounts, attaching larger end plates to the splitter and an adjustable wickerbill to the spoiler, like the Z/28’s. The Chevy team says there’s extra meat on the movable parts should the more serious owners want to drill their own holes. Juechter says that in its most aggressive setting, the Corvette makes more downforce than any other car they’ve tested in GM’s wind tunnel. Some cars GM has tested: Porsche 911 Turbo S, Ferrari 458, McLaren 12C.
Considering the capability of the optional tires, brakes, and aerodynamics, we were surprised to hear that when Pobst pulled back into the pits after his fourth lap, it wasn’t because he wanted to stop. The car had flashed an oil-temperature warning on the back straight. “So I stuck it in neutral and let it idle even though we’re going 140 mph,” he said. It’s something to be aware of if you hold wins at the 24 Hours of Daytona or SCCA World Challenge GT series and plan on tracking your Z06 on a warm, humid day. For the rest of us, the extreme level of performance available leaves plenty of headroom.
You’ll also find it bizarrely easy to drive around town. At low speeds, it’s like a normal Corvette, with nimble steering and ample cargo capacity under that hatch. The powerband’s sheer breadth means you can treat the manual like a three-speed. Dig into the infotainment system and you’ll find adjustments for the exhaust volume, from full-on freeway-droning madness to near silence. It has cooled seats. Wi-Fi, even. The price makes this all the more bewildering, as you’d need to spend nearly $1 million elsewhere to reach the performance our Z06 offers at an as-tested $105,210.
With that comes the clear message this car sends to the rest of the world: Bring it on.
Z06 to C7.R
Want another Z06 bragging right? It’s more powerful than its C7.R road racing counterpart you’ll see at the Tudor United SportsCar Championship and 24 Hours of Le Mans. The C7.R makes around 500 hp because regulations limit displacement to 5.5 liters and forbid forced induction and variable valve timing. The engine is based off the one in the C6.R and still uses a six-speed sequential transmission, but it now has direct injection, which improves throttle control and fuel economy — pit stops matter.
The same new types of aluminum construction that improve the Z06 translate to the C7.R. Using the production car’s aluminum frame increases the race car’s stiffness by 40 percent over its predecessor, according to Chevrolet. Both race car and street car chassis are built in the Corvette’s assembly plant in Bowling Green, Kentucky. The two cars look similar, too, sharing similar ideas about airflow. Never mind that the C7.R is 3.3 inches lower and 4.8 inches wider. It also omits the inlets above the production car’s rear wheels in favor of airflow.
The C7.R also dons Michelin racing slicks and smaller-diameter steel brakes with beefier braking hardware (six-piston rear calipers!), and it eschews the road car’s transverse leaf springs and MR shocks for race-specific coil-overs. As it’s a race car, it can do without the things that make commuting more pleasant — goodbye cooled seats and Wi-Fi. And despite the roughly 150-hp power deficit, the C7.R is faster.
|2015 Chevrolet Corvette Z06|
|DRIVETRAIN LAYOUT||Front-engine, RWD|
|ENGINE TYPE||Supercharged 90-deg V-8, alum block/heads|
|VALVETRAIN||OHV, 2 valves/cyl|
|DISPLACEMENT||376.0 cu in/6,162 cc|
|POWER (SAE NET)||650 hp @ 6,400 rpm*|
|TORQUE (SAE NET)||650 lb-ft @ 3,600 rpm*|
|WEIGHT TO POWER||5.0 lb/hp|
|SUSPENSION, FRONT; REAR||Control arms, transverse leaf spring, adj shocks, anti-roll bar; multilink, transverse leaf spring, adj shocks, anti-roll bar|
|BRAKES, F;R||15.5-in vented, drilled, carbon ceramic disc; 15.3-in vented, drilled, carbon ceramic disc, ABS|
|WHEELS, F;R||10.0 x 19-in; 12.0 x 20-in, forged aluminum|
|TIRES, F;R||285/30R19 94Y; 335/25R20 99Y Michelin Pilot Sport Cup 2|
|TRACK, F/R||63.0/61.7 in|
|LENGTH x WIDTH x HEIGHT||176.9 x 77.1 x 48.6 in|
|TURNING CIRCLE||37.7 ft|
|CURB WEIGHT||3,533 lb|
|WEIGHT DIST., F/R||51/49 %|
|SHOULDER ROOM||55.0 in|
|CARGO VOLUME||15.0 cu ft|
|ACCELERATION TO MPH|
|PASSING, 45-65 MPH||1.4|
|QUARTER MILE||11.3 sec @ 126.2 mph|
|BRAKING, 60-0 MPH||91 ft|
|LATERAL ACCELERATION||1.16 g (avg)|
|MT FIGURE EIGHT||22.5 sec @ 0.98 g (avg)|
|2.6-MI ROAD COURSE LAP||01:30.2|
|TOP-GEAR REVS @ 60 MPH||1,200 rpm|
|PRICE AS TESTED||$105,210|
|AIRBAGS||Dual front, side/head|
|BASIC WARRANTY||3 yrs/36,000 miles|
|POWERTRAIN WARRANTY||5 yrs/100,000 miles|
|ROADSIDE ASSISTANCE||5 yrs/100,000 miles|
|FUEL CAPACITY||18.5 gal|
|RECOMMENDED FUEL||Unleaded premium|