Among Chevrolet aficionados, you’d be hard-pressed to come up with two more significant Regular Production Options (RPO) than “Z06” and “ZR1.” From humble beginnings in the 1960s and early ’70s, both alphanumeric codes have grown to represent the very best version of GM’s best car over the past 35 years. Both have spawned four representatives since 1990, and while each code roughly translates to a faster, rarer, more expensive, more special version of Chevy’s already-fast and already-special halo model, both have fostered unique reputations and expectations among enthusiasts, But how, exactly, are they different, and which one is best? So much history and so many variables are at play that it’s up to each individual to choose, but you don’t have to go at it alone.
“ZR1” first appeared in 1970 as a handling/lightening/overall sharpening package available on C3 Corvettes equipped with the ultimate Gen-I small-block V-8, the LT-1. This legendary powerplant displaced 350 cubic inches and featured a Holley four-barrel carb, solid lifters, special forged TPW pistons, and 11.0:1 compression. It all added up to 370 horsepower and 380 lb-ft of torque. RPO ZR1 took an LT1-equipped Vette and added a mandatory M22 “Rock Crusher” four-speed manual transmission; heavy-duty brakes and suspension, which included beefed-up shocks and rear leaf springs; 5/8-inch front sway bars and rear spindle struts and stabilizer bars; a transistor ignition; metal fan shrouds; and a unique aluminum radiator. Also, in true race-car style, it deleted frivolous equipment like A/C, AM/FM radio, power steering, rear window defroster, and deluxe wheel covers. As an option, ZR1 remained in the order guide for three years, at the substantial cost of $1010—about 21% of the Corvette’s base price at the time. Just 53 were ever built: 25 in 1970, just 8 (with a lowered 9.0:1 compression and 330 hp) in ’71, and a final run of 20 in ’72, which were again diminished to 255 net horsepower.
“Z06” dates back even further, with its roots in the first year of C2 production. In addition to its famed signature Split-Window, 1963 is notable for introducing the world to the “Special Equipment Package,” RPO Z06. This brainchild of chief engineer and two-time Le Mans class winner Zora Arkus-Duntov followed in the footsteps of his early go-fast RPOs like 1957’s heavy-duty “684” and cemented Zora’s “by a racer for racers” template for cars like the ’70 ZR1 to follow. Only available on manual-transmission coupes equipped with the top-shelf 360-horse fuel-injected L84 327, highlights of the Z06 option included stiffer springs, a thicker front stabilizer bar, heavy-duty shocks, and upgraded metallic-lined brakes. An optional 36.5-gallon fuel tank was also available through RPO N03. During its one year of availability, 199 Z06s were built, with just 78 also receiving the “Big Tank.” Those numbers seem low but are impressive when considering the combined cost and general unfriendliness of the racing options. A base 1963 Corvette stickered at $4037; add in $1818 for Z06, $619 for the L84/manual combination, and $202 for the endurance tank, and a fully prepped Z06 added a staggering 65% to the car’s bottom line.
C4 ZR-1
Both RPOs would all but fade into oblivion, until ZR-1 was dusted off (complete with a fancy new hyphen) for General Motors’ 1990 American performance resurrecting “King of the Hill” project—with the helping hand of an international who’s who of suppliers. As in its 20-year-old predecessor, the best, most technically advanced, most powerful small-block V-8 at the time was the centerpiece of the first modern ZR-1. Developed in conjunction with the then-GM-owned British sports car maker and seven-time F1 Constructor’s champions at Lotus, and assembled by the aluminum manufacturing experts at Mercury Marine, the LT5 “heart of the beast” broke from nearly every Chevy V-8 convention, except for its 350-cube displacement and trademark 4.40-inch bore spacing.
It added dual overhead cams and four valves per cylinder to a Vette powerplant for the first time—and only time, until 2023—to the tune of 375 and later 405 horsepower. This at a time when run-of-the-mill Corvettes were making do with 245 ponies, and even the contemporary Ferrari 348 was only spinning out 296 hp. In addition to the monstrous tour de force of a motor, the ZR-1 featured wider haunches to accommodate more serious rubber than any Corvette up to that point had ever seen. Also included was a unique six-speed manual transmission from German firm ZF, an XL set of specialized Australian disc brakes, and a heavy-duty suspension setup that included all of the base car’s optional Z51 goodies in addition to a thicker rear anti-roll bar, as well as the “FX3” precursor to modern Magnetic Ride Control that used adjustable, gas-filled Delco/Bilstein shocks. By this time, the base Corvette’s MSRP had ballooned to $31,979, and the $27,016 ZR-1 “package” effectively doubled that number to a place that would take 16 years and a 54% cumulative rate of inflation to surpass in the Corvette record books.
C5 Z06
The excessive cost of the ZR-1 had two primary effects: declining public interest in the model after only a couple of years on sale, and within the walls of the Renaissance Center, a new primary directive to make its follow-up more accessible. It took six years after the ZR-1’s cord was pulled in 1995, but that follow-up arrived in 2001 to bring the Z06 badge into the 21st century. Compared to the superpowered all-around performer/ luxury grand tourer that was the ZR-1, the Z06 took a lightweight, track-focused approach that would continue to define its descendants for decades to come. The whole project started with the C5’s svelte but short-lived Hard Top Coupe body style and kicked things up several notches.
Again, these upgrades started under the hood, where the new base car’s revolutionary LS1 third-gen pushrod small-block was strengthened and treated to a hotter cam and higher compression, along with other minor improvements to create the 5.7L LS6, a traditional V-8 that was comparable to the LT5 but notably less expensive to produce and service. In its final 2002–04 form, the LS6 made an LT5-equalling 405 hp, along with 400 lb-ft of torque (up from 385 and 385, respectively, in 2001), beating the ZR-1’s total twist by 15. Like the ZR-1 and all performance-oriented Corvettes to come, the C5Z’s beefier engine was only the beginning.
The Z06 (now a standalone model instead of an equipment group) got a larger driveshaft, a revised clutch, and a new manual gearbox, all designed to cope with the higher demands of the LS6. A new “FE4” suspension featured stiffer front and rear antiroll bars and revised shocks compared with the base C5. Wider, grippier, non-run-flat tires were also included on the Z06, along with a set of lightweight wheels—a combination that cut some 23 pounds from the base C5’s setup. Further mass was cut through the utilization of thinner windshield and rear window glass and a calling-card titanium exhaust system à la McLaren F1. All told, the C5Z only tipped the scales at 3126 pounds, which remains a modern Vette record, and, as Car and Driver noted in its first drive, also got it within 77 pounds of the BMW M Coupe, a car 20 inches shorter, 5 inches narrower, and powered buy an engine half the size. Even with all of the extra goodness and attention to detail baked in, however, the greatest achievement of the early 2000s Corvette team led by Dave Hill was their ability to get these things into the clamoring hands of the public for only $47,500, an increase of just $7025 (just 17%) over the base targa coupe and some $20K under the MSRP of the final batch of ZR-1s.
C6 ZR1 & Z06
Everything came together, and the two Zs became forever intertwined, during the nine-year run of the C6 Corvette. After just one year off, the Z06 was the first to return, in 2006. Using the same basic recipe as its C5 counterpart, it would prioritize extra naturally aspirated muscle and weight consciousness over everything else. With the base C6 up to 6.0 liters and an even 400 horses, the second modern Z06 had to resort to drastic measures in order to establish superiority. With a 7.0-liter (427-cubic-inch) LS7 that peaked at 505 horsepower and 470 lb-ft of twist on its way to a 7000-rpm redline, not only did it put significant distance between itself and the most powerful base Vette to that point, according to Car and Driver, it “exposed the majority of European sports cars for what they are: overpriced, underperforming snobs.” For about $65,000 (a 39% surcharge on the base 2006 Vette), the car that finally one-upped the 1990 ZR-1’s shocking sticker also piled on a wide body to cover extreme rubber and brakes, the usual smattering of extra-stout driveline components, enhanced cooling and a dry-sump oil system that maintains oil pressure even in high-g cornering situations. On the diet front, Chevy was able to drop 136 pounds from base by taking the frame all-aluminum and applying magnesium to the roof and engine cradle, carbon fiber to the fenders, and crafting literal floor “boards” out of balsa wood. The result was a 3288-pound bruiser that made a habit of putting Euro blue bloods in its rearview on track and forced its crosstown rival Viper take a sabbatical to contemplate its place in the American performance hierarchy.
Upon sampling the C6 Z06, former General Motors CEO Rick Wagoner famously challenged the Corvette team by offhandedly remarking, “If that’s what you can do with $60,000, I wonder what a $100,000 Corvette would look like?” Three years later, he had his answer. For 2009, Tadge Juechter and Co. dropped an absolute bomb on the automotive industry. Unable to naturally one-up the LS7, they turned to supercharging for the first time and, in effect, took the base car’s 6.2-liter LS3 nuclear. An unfathomable 638 horses and 604 torques, along with mechanical headliners like magnetic dampers, Ferrari Enzo–spec carbon ceramic brakes, and even more carbon fiber, took the Vette right up the ladder to supercar territory as verified by its production-car record at Germany’s infamous Nürburgring.
Even as the vast majority of C6 ZR1s left the factory fully loaded, stickering for some 25% more than the pledged $100K price point, it put such a significant performance gap between itself and the existing Z06 that it decimated the market for its more attainable 7.0-liter sibling. But instead of simply dropping the Z06 and letting the supercharged car carry on as the high-end C6, Chevy engineers again rolled up their sleeves and took the generation’s original go-fast special under the knife. When it emerged from surgery in 2011, it had access to everything in the ZR1’s arsenal except the blower, making it less powerful but lighter and more focused on track. Another Z-car upgrade in 2012 brought slightly improved aero, a lighter set of wheels, and the Vette’s first foray into semi-slick rubber, allowing the ZR1 to lap the Nürburgring nearly 7 seconds quicker than before—setting another record in the process. Perhaps even more remarkable was the 2012 Z06’s 20-second improvement over its 2006 counterpart’s time, which very well nipped at the ZR1’s heels by crossing the finish line just 3.05 seconds later, despite a 133-horse deficit.
It was at this point that the diminishing returns of adding power to the traditional front-engine/rear-drive formula became glaringly evident to the Corvette team. If everything went according to plan, the seventh generation was going to be the one that finally realized Zora’s ultimate dream of taking America’s Sports Car mid-engined. But a declining economy that hit automakers especially hard had other plans. The buildup to the seventh-generation Corvette’s planned start date coincided with General Motors filing for government-backed Chapter 11 bankruptcy. In the subsequent reorganization, everything was put under a microscope. New leadership was appointed, strategies were put on hold, entire brands were axed, and even the legendary Crossed Flags suddenly faced an uncertain future. When the graciously still-intact Corvette engineering team finally received a green light to proceed with the C7 program, it came with the caveat of an extremely limited budget.
So, with the Big Daddy five-year plan of “don’t die” in mind, revolutionizing their American icon would have to wait. Instead Corvette engineers turned their attention to cost-effective upgrades for the admittedly still-excellent C6 chassis and simply stretched a new skin over the top, as most of the earmarked finances were thrown at improving interior materials and debuting the new Gen-V small-block V-8.
In a throwback to the C4 and C5 eras, only one hi-po variant was part of the original product plan. It wore a Z06 badge, but to meet targets for both power and efficiency, it hewed much closer to the blueprint laid out by the C6 ZR1. Like the “Blue Devil,” this so-called “Big Nasty” featured a supercharged 6.2-liter V-8 that now bore the LT4 name and produced a monster 650/650 horsepower/torque rating. “New GM” quashed the publishing of Nürburgring times, but at home, the C7Z upped the ante everywhere it turned a specially designed Michelin. It also opened the gates-of-Z to a more diverse customer base than ever before, because its reinforced chassis allowed it to become the first SuperVette to feature an optional convertible body style, where the coupe shares the base car’s trick removable roof panel. It also went against the purists by offering an automatic gearbox for the first time.
These Z-for-all tactics were incredibly successful from a sales standpoint, with the automatic transmission leading the charge (a 2-1 take rate over the manual) to put a staggering 39,940 C7 Z06s in the hands of customers over its six-year life cycle—more than the combined totals of its C6 predecessors, which tallied 27,995 orders for the C6 Z06s over eight years on sale, and just 4695 ZR1s built between 2009 and 2013, for a total of 32,690.
This overwhelming showroom success forced Chevrolet to resurrect the ZR1 for a special one-year-only curtain call. The desire was compounded by a certain amount of necessity—GM felt a need to make up for some early and very public issues with overheating, and it simply wanted to properly send 66 years of front-engine Corvette legacy into the sunset before finally making good on the mid-engine promise with the C8.
And what a curtain call it was. A huge 2.65-liter supercharger replaced the Z06’s 1.7-liter unit, with boost up from 9.4 to 14 psi. To get this monster its required amount of premium—and ignite some flame-throwing theatrics in the process—direct and port fuel injection were utilized. The outcome was a high-water mark for GM pushrod power: 755 ponies and 715 torques from a cast aluminum lump that was some 300 pounds easier on the scales than the contemporary Hellcat V-8s from across town. To somewhat balance out its remarkable V-8, the ZR1 was also treated to the most extreme aerodynamics package seen on any Chevrolet up to this point in the “Big Wing” ZTK package, which was capable of generating nearly 1000 pounds of max downforce. Like the Z06, it was available with targa and convertible bodies and offered the same pair of transmissions. But as history’s most expensive Vette (until 2025 ZR1 pricing is released, at least), with the world’s worst-kept mid-engine secret waiting in the wings, just 2953 ever left the assembly plant in Bowling Green, securing its status as one of the rarest modern Corvettes.
The mid-engine C8 finally hit showrooms for 2020, but outside circumstances pushed back the first of the Z-badged cars until 2023, when the C7 Z06 was officially rendered an “outlier” by its long-awaited predecessor’s return to its naturally aspirated roots. And what a return it was! The dual-clutch, automatic-only C8 Z06’s LT6 motivator took an exotic path to free-breathing horsepower that no Corvette had driven before. Dual overhead cams were back in the mix for the first time since the C4 ZR-1 bowed out nearly 30 years before, but this time, the overhead cams brought a Ferrari-style flat-plane crank, as opposed to the 90-degree crank traditionally favored by American V-8s. At 5.5 liters, the LT6 became the largest-displacement flat-plane V-8 ever installed in a production vehicle, while its 8600-rpm redline set a new bar for North American performance cars. And the pièce de résistance: Its 670 horsepower shattered the record for naturally aspirated V-8s previously held by Mercedes-AMG’s final holdout from downsizing and turbocharging, the 622-horse SLS Black Series.
This upscale new take on America’s Sports Car earned a clean sweep during industry awards season, and the high-revving masterpiece was only the tame first half of Chevrolet’s rocket Easter Egg–ridden “Gemini Project” (no fewer than 54 examples of the NASA spacecraft can be found around the LT6 engine). Its ZR1 twin broke cover earlier this year, and it raised the bar of what we even imagined was possible in an all-motor performance vehicle. With the addition of the largest turbos ever fitted to a production car, plus a different-enough engine block to warrant its own part number, the LT7 was born into a poetic split-windowed engine bay. With up to 24 psi of boost and compression down from the LT6’s 12.5:1 to 9.8:1, power skyrockets to a still-difficult-to-comprehend 1064 horses and 828 lb-ft. The former being especially notable for shooting past the numbers that the likes of Ferrari and Lamborghini are achieving only with hybrid assistance.
It converts all of those ponies into a Corvette-record 233 mph top speed, making it the undisputed greatest Corvette of all time. These are emotional cars, though, and it does them a disservice when they’re boiled down to simple numbers. Which badge has the superior history, and the examples we’d rather drive today, is up to the beholder. But if you’re looking for assistance with your scorecard, we’d call the originals and the C4/C5 battle effective draws. With the C6s, we would call for the unique and raw throwback that is the Z06. While it’s fair to debate if the ZR1 is worth the upcharge for pretty minimal performance gains in the C7 realm, the one-year wonder is a no-brainer, if you can afford it. That leaves the tiebreaker to the battle of C8s, and the ZR1 had better be ready to yank hard on some heartstrings if it is to dethrone its lighter, higher-revving NA sibling. Stay tuned, this debate will be settled soon.
They are all great cars.
But for track time the C6 Grand Sport is the one the Vette team members say is their crown jewel.
It has great power but not too much that you can put it to the track. It has great Z06 Brakes. and if it is the coupe it has a steel frame that if you nub a wall can be fixed.
It comes with the dry sump of the Z06 and ZR1 too.
These other higher HP cars are great and fun but for real track use in the hands of people that are not pro drivers less is more.
Keep in mind the C8R is much less power too.
I really would love to see the C8 in a Grand Sport version. This would give you all the good bits with good power and a lower price. Might make lighter body parts as an options to reduce mass.
I had a high-revving na motor in the E46 BMW and I loved that motor. Na and high revving is fun. Never had boost and the one time I drove a friend’s car with a massively oversized turbo (1st gen MR2 with a built motor) I was very happy I had the tires pointed the right direction when the boost hit. I think I might lean towards the na if I win the lottery
Well, I’m not going to argue about which one is best. But the ones I want most are the 1970 ZR1, the C4 ZR-1, and the C5 Z06.
As much as I like the C6 Z06, those electrically operated doors are a dealbreaker.
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