Why Most Cars Use Open Differentials

Cars come with open differentials because they are inexpensive, efficient, predictable on pavement, and adequate for everyday driving while allowing the left and right wheels to rotate at different speeds in turns. In other words, they solve the fundamental problem of cornering smoothly with minimal complexity, weight, and cost—factors that automakers prioritize for the vast majority of vehicles and drivers. Below, we explain how open differentials work, why they’re the default choice, their drawbacks, and the technologies manufacturers use to offset their limitations.

What an Open Differential Does

An open differential splits engine torque to the two wheels on an axle and lets those wheels spin at different speeds. That’s essential in turns, where the outside wheel travels a longer path than the inside wheel. Mechanically, an open diff delivers the same torque to both wheels, but the total torque is limited by the wheel with the least grip—so if one wheel is on ice, usable drive torque is capped at that low-traction side. This behavior makes open diffs smooth and predictable on high-grip pavement but vulnerable in low-traction situations.

Why Automakers Choose Open Differentials

The following points outline the primary reasons open differentials remain the default in most passenger cars and many crossovers and trucks.

• Cost and simplicity: Fewer parts, straightforward manufacturing, and easy serviceability keep vehicle prices down.
• Efficiency: Low parasitic losses help fuel economy and EV range; they also aid compliance with fleet efficiency targets.
• Packaging and weight: Compact, light designs simplify chassis layouts for both FWD and RWD platforms.
• NVH (noise, vibration, harshness): Open diffs are generally quieter than clutch or gear-type limited-slip units.
• Predictable handling on pavement: Smooth torque delivery reduces abrupt yaw moments and under/oversteer surprises.
• Tire wear: Allowing speed differences across the axle reduces scrub and extends tire life in everyday use.
• Electronics compatibility: Plays nicely with ABS, stability control, and brake-based traction systems without added calibration complexity.
• Durability and warranty: Fewer wear elements than clutch-based LSDs can mean fewer warranty risks in mass-market use.

Taken together, these benefits make open differentials a practical, low-risk baseline for most road cars, where drivers spend almost all their time on dry or wet pavement rather than extreme conditions.

Where Open Differentials Fall Short

Despite their strengths, open differentials have known weaknesses that show up in low-grip or high-performance scenarios.

• One-wheel traction limit: If one tire is on ice, mud, or lifted, effective drive torque drops to the lesser-traction wheel.
• Performance corner exits: Inside-wheel spin can waste power and slow lap times in spirited driving.
• Off-road obstacles: Cross-axle articulation can leave one wheel unweighted, stalling progress.
• Towing and steep grades: Traction asymmetry can cause wheelspin when launching heavy loads.
• AWD nuances: Axle open diffs can hamper diagonal traction unless the system uses brake intervention or clutch packs elsewhere.

These drawbacks are real but situational; most daily driving doesn’t expose them. That’s why manufacturers often supplement, rather than replace, open diffs with electronic aids.

How Manufacturers Offset the Weaknesses

Automakers commonly pair open differentials with software and selective hardware to improve traction when needed, while keeping the base system simple.

• Brake-based traction control: Briefly brakes a spinning wheel to raise the torque that the open diff can transmit to the wheel with grip.
• Electronic torque vectoring by brake: Uses targeted braking to nudge yaw and improve cornering and exit traction.
• Preload solutions: Light clutch preloads or helical gear biasing in some trims to reduce inside-wheel spin without heavy NVH.
• Active rear “eLSDs”: Electronically controlled clutch packs (often in performance models) add variable locking on demand.
• AWD couplers and center clutches: Route torque fore/aft to maintain momentum even when one axle loses grip.
• EV dual-motor setups: Sidestep the axle differential entirely by driving each wheel pair (or each wheel) independently for software “vectoring.”

These measures preserve the open diff’s core benefits while delivering traction and agility on demand, especially in slippery conditions or performance driving.

When Cars Don’t Use Open Differentials

Some vehicles opt for limited-slip or locking differentials because their primary mission demands consistent traction beyond what an open diff offers.

• Performance cars: Mechanical or electronic LSDs improve corner exit traction and reduce lap times.
• Off-road and overlanding: Locking differentials (manual or automatic) ensure both wheels turn together for obstacle clearance.
• Heavy towing and work trucks: LSDs and lockers aid launches on uneven or loose surfaces.
• High-end AWD systems: Torque-vectoring rear diffs actively apportion torque side-to-side for handling benefits.
• Certain EVs: Independent rear motors provide “software LSD” behavior without a traditional differential.

In these cases, the performance or capability gains justify added cost, weight, and complexity—trade-offs that everyday commuters rarely need.

A Quick Technical Note on Torque

An open differential always allows different wheel speeds. It sends equal torque to both axleshafts at any instant, but the maximum available torque is limited by the lower-traction wheel. Raise that wheel’s effective resistance—via a brake tap, preload, or limited-slip action—and the axle can transmit more torque to the wheel with grip.

Bottom Line

Automakers default to open differentials because they’re the simplest, most efficient, and most predictable solution for mainstream driving on paved roads. Their main weakness—limited traction when one wheel slips—is increasingly mitigated by brake-based traction control and, where needed, optional limited-slip or locking technologies.

Summary

Open differentials dominate because they balance cost, efficiency, quietness, durability, and predictable handling for everyday use, while permitting the wheel-speed differences required in turns. Their traction limitations in low-grip or high-performance situations are real but are commonly offset by electronic traction controls, optional LSDs, lockers, or, in EVs, motor-based torque vectoring.

What is open differential good for?

Open differentials offer several key advantages. They provide excellent driveability, are relatively easy and inexpensive to manufacture, and are lightweight and efficient, making them ideal for a wide variety of both front-wheel drive and rear-wheel drive vehicles, including passenger cars, light trucks, and SUVs.

Are most cars open differentials?

Open differentials are the most common differential found on passenger vehicles and allow the wheels to rotate at different speeds while the vehicle is turning a corner.

Why are open diffs bad?

Disadvantages: Open differentials don’t work well on uneven or slippery surfaces because the engine torque is transmitted to the wheel with the least resistance (a.k.a. “traction”). If the tire is off the ground or on ice, it spins freely and the vehicle is unable to move.

Is open or locked differential better?

The key advantage of a locking differential is its ability to provide maximum traction under demanding conditions. By preventing power from being diverted to the wheel with the least resistance, a locking differential ensures both wheels receive equal torque.