"You're doing 127 mph right now. That's where it should top out," chimed the Volkswagen representative from the back seat.

I was behind the wheel of a 2019 Volkswagen Jetta Mk. 7 prototype on automaker's Arizona Proving Ground's high-speed oval, foot planted and rocketing around one of the 33-degree banked turns. The facility is so top secret that most automotive journalists I asked didn't even know that it had been there for about 25 years. I was among the first press to be allowed inside and had to surrender my camera and phone at the gates.

The prototype itself was so top secret that it was covered in camouflage inside and out. So, I wasn't even allowed to look at the dashboard or instrument cluster, which is why the helpful Volkswagen employee in the back was periodically reading my current speed aloud from a GPS device.

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At and up to the claimed top speed of 127 mph, the sedan felt quite stable and actually quieter than I expected. An un-timed zero to 60-ish sprint felt okay with a nice torquey mid-range. A subsequent 60-ish to zero braking test took longer than I would have liked, but the wheel stayed straight and controllable down to a stop. Without gauges or instruments, the best I can say is that it feels quick enough.

All-new beneath the camo

The seventh-generation Jetta has finally been redesigned from the ground up using Volkswagen's new MQB platform. The sixth-generation model rides on a much older platform, despite the Golf having made the switch way back in 2012. The new modular platform -- which also underpins vehicles ranging from the compact Golf to the three-row Atlas -- allows VW to create a new Jetta specifically catered to the North American market.

The engine powering the Mk. 7 appears to be a holdover. The Jetta will be powered by a 1.4-liter TSI turbocharged engine; specific output figures haven't been stated but VW claims "class leading torque." The current Jetta Mk. 6's turbo four makes 150 horsepower and 184 pound-feet of torque, so we can expect something in that ballpark.

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Between the engine and the front wheels is a new 8-speed automatic transmission; that's two more gears than before, which should presumably improve highway fuel economy. VW stuck to a torque converter automatic rather than a DCT or CVT because it feels the traditional automatic will be a better fit for the needs and preferences of your average American driver. This is another example of how VW is tweaking the MQB platform for North America.

The move to MQB also allows Volkswagen to bring its newest dashboard and safety tech to the seventh-generation Jetta. So expect a dashboard and cabin tech that looks a lot like the new Atlas with its large MIB software and hardware. Though neither prototype I was able to test was so equipped, we can also expect the automaker's digital cockpit tech and "state-of-the-art" driver assistance technologies to make their way to the options sheet.

Testing the handling

Tires thoroughly kicked, I was next able to test the prototype on VW's wet skid pad and a handling course. Without instruments, I'm left using touchy-feely terms to describe a seat-of-the-pants feel. Bear with me.

On the skid pad course, I was able to toss the Jetta through a wet cone chicane to get a feel for how it handles in the rain. The car felt nice and stable. I tried a few bone-head moves to see how the sedan dealt with it and found the Jetta to be predictable. Braking or goosing the throttle mid-turn, the Mk. 7 responded with progressive and easily correctable understeer. No surprises and no spinning. Under hard braking and acceleration, the Jetta stayed nice and straight, even when the wheels had differing levels of grip.

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The dry handling course was a narrow bit of track with lots of off-camber turns and too tight corners. It's a low-speed course that wasn't really designed to evaluate performance handling, but I made do.

While I wasn't able to push the limits of the Jetta's handling, I was able to once again see what happens when you make the sort of simple mistakes that the average driver does. I came into corners too hot, braked at awkward moments and jerked the wheel mid-turn to avoid imaginary potholes. After my experience on the wet pad, I wasn't surprised to learn that the Jetta responded to all of my intentional goofs with more of that predictable and easily correctable understeer.

When I wasn't trying to throw ham-fisted curveballs at the Jetta's suspension engineers, the sedan felt good. It's comfortable and quiet and corners neutrally. That's exactly what you want from a volume seller.

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We'll learn more about the new 2019 Volkswagen Jetta and see it without the camouflage when it takes the stage at the 2018 Detroit Auto Show next month.