The Electric Future Of Off-Roading Looks Bright (Video)

Last week, Jeep lent us a Wrangler 4xe, in top Rubicon trim. While the 4xe isn’t a full EV (it’s a plugin hybrid), it does give 20-30 miles of EV range in our testing. When we took the vehicle out on rough trails under nothing but electric power, we realized pretty quickly that we were driving the first serious off-road mass produced EV.

Vehicles like the Cybertruck, Rivian R1T and R1S, Bollinger B1, and upcoming full electric Jeeps are going to have more electric range, but they aren’t available for anyone to buy or even test today. So, the Wrangler 4xe really gives us the only taste we can get of what’s to come.

With that taste, we learned that there are three big advantages to electric vehicles over ICE off-road, and have one important question that’s not yet answered.

Here’s a quick summary video (I’ll go more in-depth on each topic after the video):

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Advantage #1: Low Speed Control Climbing Obstacles

The first thing I noticed off-roading under electric power was just how much easier it was to climb up rocky surfaces and obstacles. An electric motor can get power at zero RPM, and you can control how much or how little power you give. You can give a very small press of the pedal and get just the right amount of power to climb an obstacle and not come slamming down the other side.

An ICE vehicle can’t do this because their engines can’t run at zero RPM. If they go below 500 RPM or so, they’ll stall. To be able to go 0-5 MPH or so, the vehicle’s transmission must allow slip in the connection between the engine and the wheels. In a manual transmission, you adjust and manage the slip with the clutch pedal until there’s enough speed to not stall the engine, and then let the connection be direct. In an automatic transmission, a torque converter allows the slip to occur:

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The constant load on the torque converter when the car is sitting still is what causes “creep.” The moment you let off the brake, a car with an automatic will start to push itself forward. When an EV creeps, that’s actually a program in the vehicle’s computer designed to give a little bit of power to imitate a car with an automatic transmission, and not a torque converter working.

If you’ve ever started driving an ICE vehicle with an automatic transmission up a hill, you’ve probably noticed that you have to give it some more power to get it moving. The idle “creep” doesn’t have enough power to push the car up the hill, so you have to rev it up a bit to get things moving. We can call this “loading” the torque converter.

When you’re climbing obstacles, this can be problematic. You have to give the ICE some gas to load up the torque converter and start the vehicle to moving over the obstacle. Unfortunately, the moment you get to the top, all that pent up power in the torque converter isn’t pushing against as much gravity as before, and you’ll get a sudden burst of speed if you’re not careful to let the gas back off right before the tire crests the obstacle. If there’s too much power pent up, and the vehicle surges over the top of the obstacle, you’ll have to jam the brake to stop it from popping over the other side and slamming the vehicle down.

The Wrangler 4xe doesn’t have a torque converter, because the electric motor doesn’t need any slip. You can’t stall an electric motor, so it can start producing torque and moving the vehicle right from zero RPM. This allows the driver to very gently climb an obstacle without a sudden surge of acceleration at the top.

This greatly improves the driver’s ability to control the ascent up a hill with obstacles, and saves a lot of trouble.

Advantage #2: Regenerative Braking

When you start descending a hill, regenerative braking is a big help. On steeper hills, you’ll still need to use friction brakes to control your speed, but even then the instant braking effect once you let off the accelerator helps a lot. On the Wrangler 4xe, heavy regen isn’t enabled by default, but it’s available with the push of a button. Future off-road EVs will have similar features.

Because regenerative braking doesn’t have quite the “bite” that regular braking does, it’s a lot harder to slide on a downhill with loose material. For off-roading, this helps a lot because you’ll frequently encounter steep downgrades with loose rocks, gravel, or dirt. Even on steep hills where friction braking is required, being able to only add light friction braking instead of relying on them completely helps keep sliding at bay.

Advantage #3: Stability At Higher Speeds

The Wrangler 4xe doesn’t use a dedicated EV platform, and is not a “skateboard” design. That having been said, it’s probably better that they didn’t try that. Putting something as valuable as your battery pack that low would almost certainly lead to scraping and pack damage on more technical trails. Despite this, the 4xe still gains advantages over the regular Wrangler.

For the Wrangler, the pack helps in two ways. First, it’s still mounted low enough to lower the vehicle’s center of gravity. Second, its placement toward the back balances out the weight of the four-cylinder engine, making for weight distribution much closer to 50:50 than other Jeeps. Between these two things, the vehicle is not only a lot better at handling on roads, but is better for higher speed off-road driving on trail stretches without big obstacles.

For future electric off-road vehicles built on a dedicated architecture, these advantages will probably be even more magnified, assuming they don’t leave the vehicle vulnerable to damage.

Big Questions Left Unanswered

This leads us to one big question that’s left unanswered: Will future off-road EVs be built to withstand serious off-roading? And this question raises a bunch of related questions. As they say, the devil is in the details.

Vehicles built for off-road use will, like today, come built in a variety of ways. Some will be lifted “skateboards.” Others will be built more like the Wrangler 4xe, with a traditional body-on-frame architecture and solid axles. Others will be some mixture or a novel design we don’t see much of today. Each of these designs (when designed properly) will have advantages and disadvantages.

Independent Suspensions & Drive Units

The biggest issue I’m wondering about at this point is whether the now common practice of transverse drive units with independent suspensions will work out well for off-roading. We already know that the Tesla Model X has problems with premature CV joint/axle wear when people drive it around on the “high” suspension setting too much, and that’s ultimately the problem: CV joints don’t fare well when they aren’t mostly kept level. Do too much wheel travel under power or lift a Cybertruck, and you’ll have problems with not only wear, but the binding of CV joints.

Gas-powered trucks and SUVs with independent suspensions deal with this same problem when people install aftermarket lift kits, but the solution for those is pretty simple: lower the differential (the part in the middle that sends power to the wheels) to flatten out the CV joints’ angles. With a Tesla-style EV, doing a lift of more than an inch or two will require the whole drive unit be lowered, and I’m not sure how practical or safe that’s going to really be.

Aftermarket kits may solve this with lowering mounts, some metal armor to protect the aluminum drive unit, and any needed extensions to electrical, cooling, and other systems. Cheaper kits (along with some factory vehicles) might experience problems, though.

Bollinger solved this problem by using a hybrid portal axle. The CV joints go out toward the wheels laying flat, and a planetary gear takes the power from axle to lower wheels, much like an HMMWV. This allows for greater ground clearance while not destroying CV joints.

The cheaper, and likely better option for a serious off-road vehicle would be to just go with the tried and true solution of solid axles and a transfer case like the Wrangler 4xe. Have a single electric motor feed power into a multi-speed transmission, which feeds the transfer case. Sure, this wouldn’t be high-tech, but it would be rugged, durable, and get the job done, while being easy to lift and modify for more extreme trails.

Battery Pack Safety

Another important question will be how to keep battery packs from being destroyed on the most challenging trails. If slung low in the “skateboard” configuration, some serious metal armor needs to be installed under the pack to keep the vehicle from committing Seppuku on the first sharp rock it hangs up on.

The problem is compounded by heavy electric vehicles. With the extra weight of the battery pack and balanced weight, that much more force will be pushed into the battery pack if the vehicle slams down onto a rock under the center of the vehicle. This means that even thicker plating will be needed to prevent $20-30k worth of damage.

Other things under the body, like coolant connections, wiring connections, and drive units will also need some form of protection to prevent serious damage.

While multiple methods will be used, it may be that the skateboard configuration won’t always be a good solution for an off-road EV.

Assist Features

For serious off-roading, we found that on several occasions we’d have problems with Jeep’s assistance features. Traction control turned off by default when the vehicle was shifted into 4-Low, but a hidden menu item, called “Hill Start Assist.” gave us some problems on the worst hills.

One thing that’s going to be critical is to allow users to quickly turn assistance features on and off. If these features are buried deep in some menu on a touch screen, it will be a huge hassle.

Final Thoughts

There’s obviously a lot of potential in off-road EVs. In most respects, they’ll be a superior choice to their ICE counterparts. If a vehicle is made well for off-road duty, it will be a clear choice. The problem is that not all manufacturers are going to get this right. We don’t know who is going to screw this up, but we’ve seen ICE manufacturers do this wrong, and will most certainly see at least one off-road oriented EV executed particularly poorly.

The market will sort this out, but hopefully it isn’t one of the early entrants that screws the pooch. The reputational damage from one poor EV could keep serious off-roaders away from electrification for decades. We need to be sure to keep pressure on manufacturers to make sure they don’t sell too many bad designs marketed for off-road use.