Turn right here and then feel free to get up to 50 mph. That’s what Toyota Senior Engineering Manager Jakin Wilson said to me as I pilot a Tacoma Trailhunter through a lumpy dirt trail, replete with sudden peaks and troughs, terrain changes, and sweeping bends.
I gleefully rocketed up to 55 mph, maxed out the suspension travel, and worked the Old Man Emu shocks. Undeterred, Wilson smiled with approval. This occurred, by the way, after I descended down a 20-degree river rock hill and before crawling around a patchwork of rock and roots on a winding two-track path.
All of the above made up but one section of a massive proving grounds outside of Whittmann, Arizona, about 90 minutes from Phoenix and seemingly in the middle of nowhere. Toyota recently completed a remodel of the facility and expanded the off-road test areas in the process. That’s in addition to a new 5.5-mile oval track, resurfaced ride and handling loops, and a new pass-by noise area.
Considering my own engineering experience, I gleefully accepted an invitation to spend the day at Toyota’s newest playground and jumped on a westbound plane toward Phoenix. What does this updated proving grounds say about Toyota’s direction for the future? Time to find out.
In Short: Toyota Arizona Proving Grounds
Toyota showcased its expansion of hydrogen fuel cell tech and how it continues to invest in U.S. development of new products. While the Toyota Arizona Proving Grounds (TAPG) facility proved well equipped to handle the entire product line, with several important on-road loops. The off-road portion proved the most entertaining.
Based on what I saw, I’m quite confident to say that Toyota off-road and overlanding will remain a very strong portion of the company’s lineup. Look no further than more Woodland, Trailhunter, and TRD-labeled models entering the fold.
- Location: Near Whittmann, Ariz.
- Size: 11,650 acres (approx. 18.2 square miles)
- Facilities: Vehicle dynamics area, road and handling course, 5.5-mile oval, pass-by noise loop, coast down loop, ride surfaces, steep incline and decline slopes, several off-road trails, and much more
- Paved test surfaces: 77 miles
- Off-road and dirt tracks: More than 50 miles
- Investment: More than $50 million
Pros
- Well-isolated facility with plenty of space
- Nice variety of off-road trails
- Open to other companies to rent and use the grounds
- Open year-round
Cons
- An hour from the outskirts of the nearest large city
- 120-degree weather in the summer
- Virtually zero natural shade
Flinging Mud
Toyota showcased several different paved surfaces across its updated facility, but — clearly — I saw the most excitement emanate from the off-road engineers and the over 50 miles of trails, paths, hills, and obstacles at their disposal. To experience a taste, I got behind the wheel of a Tacoma TRD Off-Road and then a Tacoma TRD Pro, to ascend a dirt hill, only to then descend a hill of jagged, uneven rocks.
Both the Off-Road and the Pro accomplished the task of driving down the uneven, suspension-stretching surface. And both used CRAWL control technology to maintain an even speed without my feet having to intervene on either pedal.
But the Pro handled the task faster and with less drama courtesy of iso-dynamic seats, which absorb some of the energy, which would otherwise jostle the driver. I appreciated feeling the benefits of these seats. On the road, they feel the same as normal seats and sap second-row foot room in the process.
The real treat involved bombing around in the Tacoma Trailhunter over a few miles of rugged terrain enveloped by TAPG property line fences. Covering 5 or so miles, engineers had me traverse over tree roots and bathtub-sized divots, only to then hit the gas and bound over sharp undulations on a wider dirt trail, working all of the Trailhunter’s suspension travel and the Old Man Emu shocks.
While this particular path stayed fairly flat, I saw several steep hills of all kinds of surfaces throughout the grounds. What I experienced was but an amuse-bouche of what the engineers utilized to tune all the various off-road variants of Tacomas, not to mention 4Runners, Land Cruisers, Tundras, Sequoias, and more.
The Return of Scion?
Making its debut at SEMA, Toyota brought its Scion 01 side-by-side concept to Arizona to stretch its legs a bit. While there, I got a chance to speak with the Vice President of Vehicle Performance Development, Don Federico. In that conversation, I learned a lot of new details about this off-roading toy.
I asked him what makes this concept tick. Federico, pleased to chat, dove right in. “We’re going to start with the exciting stuff, what’s pushing it. The big story here is, lots of off-the-shelf parts,” he said. “We looked at the back of the Scion 01. We’re looking at the powertrain; that’s a 2.4L turbo hybrid that comes out of our Tacoma.”
That’s the higher of two powertrains offered in Toyota’s midsize truck, making a healthy 326 horsepower and 465 pound-feet of torque. It also uses the same eight-speed automatic transmission and battery pack.
In fact, because the Scion 01 weighs considerably less than a Tacoma, it will drive “a few miles” on electricity alone, according to Federico. Toyota calls it silent mode.
Distinctly not off-the-shelf, Fox shocks are mounted on a custom-built rectangular and tubular frame that offers 17 inches of ground clearance and a full 26 inches of suspension travel. “And there’s no trickery here,” Federico said. “That’s a full 26 inches, no tire squish; you get that full stroke on there.” Hanging out way in the corners, a set of 35-inch Maxxis Carnivore tires.
Back to plucking from the parts bin, the Scion 01 uses Camry brakes, GR Yaris calipers, Highlander hubs, Corolla power steering, and more. Inside, the concept makes use of a Tacoma shifter, mode selector, and several bits for switchgear and the like.
The in-house frame also includes a robust rollcage to protect up to four passengers (two passengers for each of the two rows) that is fully welded and both SCORE- and FIA-compliant. For good measure, the interior also includes four-point harnesses and race-style seats, up to 1,500 W of available A/C power, and reverse-opening doors to hop in. The Scion looks cool, comfortable, and very capable. Toyota, please build this!
Towing-Friendly Driving Aid Tech
Debuting on the sixth-generation 2026 Toyota RAV4 is the Toyota Safety System 4.0 or TSS 4.0 driving aid system. It utilizes cameras and RADAR with a wider field of view. It also has new software and hardware to make the system more user-friendly, especially while towing a trailer. And much of the work to develop it happened right in the U.S., here in Arizona.
To start, TSS 4.0 now automatically detects a mounted trailer and disables the rear SONAR system to avoid constant beeps and other nuances. Yet the front SONAR remains on and running to help you out. That alone is a win. Additionally, 4.0 will also continue to operate lane-trace assist, its lane centering technology, while towing. And the system even accounts for trailer sway. Helpful.
Of course, it’s not only improvements while towing. The digital instrument cluster will now more specifically show you what the vehicle detects on the road around it. If it sees a pedestrian, bicyclist, car, or semi-truck, that’s what the screen will display.
We get generally more intuitive graphics and simplified commands, too. For example, you no longer have to hold the turn signal stalk down for 3 seconds for an automatic lane change; just a quick tap initiates the command.
Hydrogen Power
At the grounds, a 100-foot by 50-foot tent structure functioned as the home base for the day. Under and next to them, Toyota installed a large PA system, lights, screens, and several other elements to keep folks comfortable for the day. And a Tundra powered it all. Well, a hydrogen fuel cell and battery pack in the truck’s bed did.
Using several external high-pressure hydrogen tanks, a fuel cell stack outputted over 600 V and 13.9 kW of power. This supplied DC electricity to inverters and on all the aforementioned needs, as well as a 28kWh battery pack, which helped keep the flow consistent.
Of course, Toyota also sells the Mirai, its fuel-cell car. But we also got to see — and ride along in — a fuel cell class 8 semi-truck. Toyota powered that truck with a fuel cell stack, which generates 170 kW. The stack gets its energy from six hydrogen tanks located where you’d expect a sleeper cab. To make it a hybrid, the truck also housed a 220kWh battery pack on the frame where you’d expect the diesel tanks.
That energy source combination powers two electric motors that output a respectable 416 horsepower (310 kW) and a mighty 1,475 pound-feet (2,000 nm) of torque. Moreover, Toyota claims its class 8 will tow 40 tons over 400 miles between fill-ups. And, those fill-ups will take less than 10 minutes. By the way, it’s a hybrid, not a plug-in hybrid. The battery pack solely gets charged by harnessing energy under braking and steady-state driving from the stack.
It’s also much quieter, smoother, and easier to live with. Oh, and did I mention quicker? I saw this truck on TAPG’s massive vehicle dynamics pad, where I sat in the passenger seat as it drag-raced and easily beat a diesel-powered equivalent truck — both of them hauling 40 tons at the time. It felt remarkably drama-free considering that well over 160,000 pounds went wheel-to-wheel.
Toyota Arizona Proving Grounds: Summary
Of course, TAPG also includes 77 miles of paved roads. That includes a 5.5-mile oval, a ride and handling loop, and a slew of other drive loops and facilities to reliably and repeatedly test systems to make vehicles better.
After spending the day here at the renovated grounds that first opened in 1993, I concluded two things. First, Toyota sees the United States as much more than an important region to sell vehicles, but also one to design, engineer, and build them.
Two, off-road capability, variety, and diversity, will continue to see a lot of the brand’s focus. No matter where and how you plan to head outdoors, if you do it in a Toyota, chances are engineers tested it at TAPG.
