Watch the 2017 Camaro ZL1’s Fuel Gage Drop on a 173-MPH Top Speed Run

John Hennessey does not usually get excited about a car he has not modified, but the 2017 Camaro ZL1 earned an exception. In this test drive, he runs the supercharged 650-horsepower Camaro through every gear on a public road, reaching a top speed that still gets cited in owner forums today. The explanation for why it stops exactly there is the most interesting part of the whole run. Watch to see how close a factory Camaro really gets to supercar territory.

Most factory test drives end with a shrug and a spec sheet. This one ends with the needle buried well past anything a stock Camaro buyer would expect to see on a public road, captured on camera by a man whose entire career is built on making fast cars faster. John Hennessey does not usually get excited about stock vehicles — his business exists to modify them — but something about the 2017 Camaro ZL1 pulled him behind the wheel anyway. The number he reaches by the end of the run surprised even people who follow his channel closely, and the explanation for why it stopped exactly there turns out to be more interesting than the number itself.

A Supercharged Heart Under a Familiar Face

The sixth-generation Camaro ZL1 that Hennessey tests here pairs a supercharged 6.2-liter LT4 V8 — the same basic architecture found under the hood of the C7 Corvette Z06 — with a choice of a ten-speed automatic or a genuine six-speed manual gearbox. Rated at 650 horsepower and 650 lb-ft of torque straight from the factory, it was, at launch, the most powerful Camaro General Motors had ever built, a claim that mattered enormously to a channel built entirely around chasing bigger numbers for a living. For Hennessey, whose shop routinely pushes vehicles past 1,000 horsepower, a bone-stock car earning this kind of attention says something about how far GM’s engineering had come.

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Why 173 MPH Is Not the Whole Story

In the description accompanying this drive, Hennessey Performance addresses a debate the video itself sparked: whether 173 mph represents the ZL1’s true top speed. Their answer is that it depends entirely on gearing. Running the six-speed manual through fifth gear yields 173 mph, but shifting into the tall sixth gear actually slows the car down, because it drops out of the engine’s effective power band before it can build more speed. A different rear-end ratio, taller tire, or higher rev limit, they note, could realistically push a manual ZL1 toward 185 to 190 mph.

The Automatic Tells a Different Story

Hennessey’s team points to a separate data point that complicates the manual car’s result here: a ten-speed automatic ZL1 was independently clocked at 181 mph on a Nurburgring straight, a full eight miles per hour quicker than the manual example filmed in this test. The automatic’s extra ratios let it stay inside its effective power band more efficiently at high speed, a quirk that surprises plenty of enthusiasts who assume a manual gearbox is always the faster choice in a flat-out run.

Fuel Gauge as an Unlikely Character

Commenters latched onto an unglamorous detail buried in the run: the fuel gauge visibly dropping as the ZL1 holds triple-digit speeds for an extended stretch of road. It is a small, honest touch that separates this footage from a polished manufacturer commercial — a reminder that sustained high speed is a real mechanical event with real fuel consumption, not a simulated number pulled from a spec sheet or a marketing brochure. Few factory test drives bother to show that side of the equation at all.

Hennessey’s Own Business Depends on Cars Like This

Hennessey Performance built its reputation modifying vehicles like the Camaro, the Dodge Challenger Hellcat, and Ford’s Raptor pickup into six-figure-horsepower machines, and Tuner School — the company’s own driving and tuning academy, complete with a chassis dyno cell and a quarter-mile dragstrip on-site — trains the next generation of builders to do the same. A factory ZL1 running 173 mph bone stock is, in that context, both a benchmark and an invitation: proof of how capable GM’s engineers made the car before Hennessey’s shop ever touches it.

Where the ZL1 Sits Against Its Rivals

At the time of this test, the ZL1’s 650-horsepower factory rating trailed the contemporary Dodge Challenger SRT Hellcat’s 707 horsepower on paper, but the Camaro’s lighter curb weight and standard Magnetic Ride Control suspension gave it a genuine handling advantage the Hellcat could not match on a road course — a trade-off between straight-line bragging rights and outright control that owners of both platforms still debate in forums to this day.

A Number That Still Holds Up

Nearly a decade on, 173 mph from a factory car with zero aftermarket modifications remains a genuinely rare figure for anything short of a dedicated supercar, and it helps explain why the sixth-generation ZL1 has become one of the most respected factory Camaros ever built among collectors who prize stock, unmolested performance over modified builds. Values for clean, low-mileage examples have held up accordingly in the years since the sixth-generation Camaro — and the ZL1 badge along with it — wrapped up production in 2024.

A Test Drive That Became a Reference Point

Years after it was filmed, this test still gets cited in online debates about ZL1 top speed, cropping up whenever someone asks whether the manual or automatic version is quicker in a straight line. That staying power is unusual for a single dealership-style test drive, and it speaks to how thoroughly Hennessey’s explanation in the description — covering gearing, tire height, and rear-end ratio — settled a question owner forums had been arguing over for years before this video existed.

The ZL1 Name Carries Its Own History

The ZL1 badge did not start with this generation of Camaro. It first appeared in 1969 on a handful of aluminum-block, 427-cubic-inch race cars built almost exclusively for drag-racing homologation, cars so rare and so expensive when new that Chevrolet built barely more than 60 examples. Reviving the name in 2012, and again for this 2017 sixth-generation car, was Chevrolet’s way of signaling that the ZL1 badge still meant the most extreme, least compromised version of the Camaro lineup — a lineage this test drive, however casually filmed, was quietly reinforcing every time the speedometer climbed past another milestone.

Not the Track-Focused 1LE, Just the Standard Car

It is worth noting this test uses the standard ZL1, not the more extreme 1LE track package that arrived a year later with a bigger front splitter, a track-tuned suspension, and even more aggressive gearing. The 1LE trades outright top speed for cornering grip, making the base ZL1 tested here the version better suited to exactly this kind of top-speed run. Knowing which variant is on screen matters for anyone trying to compare this result to other ZL1 videos circulating online, since the two cars behave very differently once the road stops being straight.

Watch the full video and tell us what you think — comments are open below.

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