Windshield Dyno: The Beltronics GX2

Adding performance goodies to your vehicle is relatively easy. For the die-hard do-it-yourselfer, it’s simply a matter of setting aside an afternoon and getting your hands dirty. For the less initiated, a quick phone call to the local tuning shop should get the job done. But once you’ve got the goods installed, how do you measure their effectiveness?

I don’t know about you, but my butt-dyno is in need of some serious recalibration (“This new washer fluid feels like it added 8 or 9 horsepower!”). With an inaccurate butt-dyno, the next most obvious option is to use a vehicle chassis dynamometer. Taking your vehicle to a dynamometer is both cumbersome and inefficient – you’ll need to make several “runs” on the dyno, all the while allowing for sufficient cool-down time. And to make matters worse, dynos are usually a hot commodity, so your time may be restricted by the shop’s schedule.

Luckily, there’s a solution for those who like to test performance improvements themselves. The solution comes by way of the Beltronics Vector Pro GX2 Performance Computer. Gone is the guessing: “Does this feel faster than before? Do I need to go one heat range lower on my spark plugs?” Gone is the frustration of hearing, “Sorry, the dyno’s booked solid until two weeks from next Thursday.”

With the Beltronics GX2, all you’ll need is a quiet, preferably secluded section of road (or better yet, a racetrack or large, empty parking lot) and some time. Within seconds of attaching the GX2 to your windshield, you’ll be enjoying instant feedback about your vehicle’s performance, and thanks to the GX2’s long list of rich features, you’ll learn more about your car’s performance capabilities than you could ever dream of learning from the dyno.


If you’re expecting something big and clunky, you’ll be disappointed with this accelerometer. The Beltronics Vector Pro GX2 is compact, measuring only 5-1/2-inches “long” by 1-1/2-inches “tall” and 1-1/2-inches “deep.” It mounts to the windshield by way of three very robust suction cups and an adjustable, drilled aluminum bracket. The entire assembly weighs just under five-ounces, including the bracket and suction cups.

Once powered (by way of a 12-volt, cigarette-lighter plug) the GX2 lights-up with a bright, 2-line vacuum fluorescent display that’s easy to read, even in direct sunlight. The large push buttons on the unit are easy to use and the menus are easy to navigate. Thoughtful features with the GX2 include the 6-foot coiled power cord that terminates into a RJ-11 (telephone-style) connector and the “remote control” buttons that are built-in to the 12-volt adapter.


The true beauty of a quality accelerometer lies not in the packaging or the marketing, but rather, in its ease of use. And to that extent, the Beltronics VectorPro GX2 is the easiest accelerometers to operate that we’ve ever tested. Calibrating the device requires nothing more than a level surface on which to park your vehicle and a finger that’s capable of pushing a button that’s marked “Calibrate.” Simple. Best of all, the unit remembers the calibration settings even if the power is disconnected – calibration is a one-time ordeal, unless you decide to move the mounting location (or transfer the unit to another vehicle).

Ok. The unit’s attached to the windshield and calibrated, so what’s next? Press the start button, wait for the unit to tell you it’s ready and mash the gas pedal. That’s it? In effect, yes. The GX2 is one smart cookie – it can determine if you’re conducting 0-60 runs, quarter-mile tests or any variation thereof. The intelligent accelerometers automatically record all run data until you either: (a) stop accelerating, (b) travel a 1/4-mile, (c) your run lasts longer than 30 seconds or (d) you press the start/stop button again.

Further, if your top speed for a given run was less than 60 miles per hour, the GX2 will tell you your time to the highest “even-10mph” speed. For example, if your top speed was 34 mph, the GX2 will calculate and display your 0-30 mph time. It does all of this automatically, requiring no programming or intervention by the end user – how cool is that?

Reviewing run results is simple, thanks to the 10-run memory and the easy to use up/down navigation buttons. The GX2’s run-data memory is also retained in the event the unit is powered off, another welcome and handy feature.

The GX2 ain’t no one-trick pony – no sir. In addition to recording straight-line times and speeds, it can measure cornering forces (your own personal skid-pad), braking distances, horsepower and much more. And just like the acceleration tests, utilizing these other features is simple and straightforward.


We decided to utilize my 2002 Volkswagen GTI 337 as the official test mule for the Beltronics VectorPro GX2. With a snappy 1.8-liter turbo that’s benefited from a few aftermarket goodies, a six-speed transmission and large 18″ wheels wrapped in sticky Michelin Pilot Sport tires, it seemed the most logical choice.

We moistened the suction cups, stuck the unit to the windshield, pressed the calibration button and set about conducting various runs and measurements. Ambient conditions were ideal – air temperature was 58 degrees Fahrenheit with 31% humidity. Perfect testing conditions.

We also went through the GX2’s G-Meter options to set the vehicle’s weight, determine the coefficient of drag (this provides a more accurate horsepower calculation) and tweak a few other settings, based on our past experiences with fifth-wheel measuring devices. Total time to complete the installation, calibration and set-up: 2 minutes, 8 seconds.

With the unit completely calibrated, we headed off to an abandoned airfield (there are plenty in our area) and began testing. The first thing that we discovered was that yours truly is not the best at launching a vehicle from a standstill. We tried it with traction control on, off, at high rpms, low rpms, and every other combination imaginable. We eventually lowered the tire pressure to 30psi (from 35psi) and accepted the fact that we wouldn’t get very good 0-60 times because despite the warm ambient temperature, the January pavement was only retaining 64-degrees of heat. Darn winters…

We made a handful of sample 0-60 runs and evaluated the data. Navigating the results was simple and easy, and much to our pleasure, the meter appeared to be providing very accurate and consistent results. And then, after the sixth “official” timed run, I stumbled across the best launching technique, and rattled off a group of 5.9 second 0-60 runs, thus matching the results from the professional fifth-wheel measuring device we had used in our full review of the 2002 GTI 337 last year.

Quarter-mile results were equally accurate to the fifth-wheel – we averaged runs of 14.60 – 14.65 seconds, with terminal speeds of between 100.5 and 101.5. But as mentioned earlier, there’s more to the GX2 than just measuring straight-line speeds. Our meter indicated that the GTI was putting down 172 wheel horsepower (again, confirmed by a previous dyno run that indicated 175.3 horsepower), and it confirmed what he had long suspected about the car’s braking system – it’s phenomenal. We wrangled the GTI from 70 mph to 0 in just 153 feet (this is due in large part to aftermarket pads and super sticky tires).

The GX2 was able to measure lateral acceleration with ease, indicating .87 g’s on our 300-foot circle (averaged in each direction). G-force readings can be read “real time” as you drive, by simply selecting one of a few available display options from the GX2’s menu. The display can also be changed “on the fly” to show everything from peak g-forces, best 0-60 times, and more.


We were extremely impressed with the Beltronics Vector Pro GX2 – so much so that we’ve decided to employ it as our full-time vehicle performance meter. The ease of operation combined with the highly accurate readings and brilliant display make it a no brainer, especially when compared to the bulky, complex and pricey alternative of a fifth-wheel system.

Whether you’re a performance junkie or someone who enjoys learning as much as they possibly can about their vehicle, it would be in your best interest to check out the Beltronics Vector Pro GX2. With a street price of well under $250, this will be the best money you’ll ever spend on improving both you and your vehicle’s performance. For more details and specifications, visit:


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