automotive design Automotive design is the process of developing the appearance (and to some extent the ergonomics) of motor vehicles, including automobiles, motorcycles, trucks, buses, coaches, and vans. The functional design and development of a modern mot ...

, dual-motor, four-wheel-drive layout is mainly used by

battery electric vehicle A battery electric vehicle (BEV), pure electric vehicle, only-electric vehicle, fully electric vehicle or all-electric vehicle is a type of electric vehicle (EV) that uses electrical energy exclusively from an electric vehicle battery, on-boa ...

s by having two

electric motor An electric motor is a machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a electromagnetic coil, wire winding to gene ...

s that each drives the front and rear

axle An axle or axletree is a central shaft for a rotation, rotating wheel and axle, wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In ...

, creating a

four-wheel drive A four-wheel drive, also called 4×4 ("four by four") or 4WD, is a two-axled vehicle drivetrain capable of providing torque to all of its wheels simultaneously. It may be full-time or on-demand, and is typically linked via a transfer case pr ...

layout In general terms, a layout is a structured arrangement of items within certain limits, or a plan for such arrangement. Specifically, layout may refer to: * Page layout, the arrangement of visual elements on a page ** Comprehensive layout (comp), ...

. This is made possible by the smaller size of electric motors compared to

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

s (ICEs), which in addition are also accompanied by a bulky

engine cooling Internal combustion engine cooling uses either air or liquid to remove the waste heat from an internal combustion engine. For small or special purpose engines, cooling using air from the atmosphere makes for a lightweight and relatively simple syst ...

system, allowing it to be fit more versatilely into multiple locations. The use of separate motors for the front and rear

drive wheel A drive wheel is a wheel of a motor vehicle that transmits force, transforming torque into tractive force from the tires to the road, causing the vehicle to move. The powertrain delivers enough torque to the wheel to overcome stationary forc ...

s eliminates the need of a

drive shaft A drive shaft, driveshaft, driving shaft, tailshaft (Australian English), propeller shaft (prop shaft), or Cardan shaft (after Girolamo Cardano) is a component for transmitting mechanical power (physics), power, torque, and rotation, usually ...

that is ubiquitous in four-wheel drive ICE vehicles, freeing up space for bigger battery modules, which are commonly mounted on the

chassis A chassis (, ; plural ''chassis'' from French châssis ) is the load-bearing framework of a manufactured object, which structurally supports the object in its construction and function. An example of a chassis is a vehicle frame, the underpart ...

floor between the axles. The dual-motor layout is beneficial in re-distributing torque and power to maximize effective

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...

in response to road grip conditions and

weight transfer Weight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects: *the change in load borne by different wheels of even perfectly rigid vehicles during acceleration *the change in center of mas ...

in the vehicle. For example, during hard acceleration, the front motor must reduce

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

and power in order to prevent the front wheels from overspinning as weight transfers to the rear of the vehicle. The excess power is transferred to the rear motor where it can be used immediately. The opposite applies when braking, when the front motor can accept more

regenerative braking Regenerative braking is an energy recovery mechanism that slows down a moving vehicle or object by converting its kinetic energy or potential energy into a form that can be either used immediately or stored until needed. Typically, regenerativ ...

torque and power. However dual-motor vehicles usually have less range for the same battery size than single-motor designs. In addition, electric vehicles may be equipped with more than two electric motors to achieve greater power output and superior handling. The first mass-produced triple-motor layout was introduced on the Audi e-tron in 2020, which consists of one motor at the front and two motors at the rear. A rare example of a non-electric vehicle utilizing this layout is the Citroën 2CV Sahara, which has two

flat-twin A flat-twin engine is a two-cylinder internal combustion engine with the cylinders on opposite sides of the crankshaft. The most common type of flat-twin engine is the boxer-twin engine, where both pistons move inwards and outwards at the same ti ...

petrol engine A petrol engine (gasoline engine in American and Canadian English) is an internal combustion engine designed to run on petrol (gasoline). Petrol engines can often be adapted to also run on fuels such as liquefied petroleum gas and ethanol blends ...

References

{{Automobile layouts Car layouts Four-wheel drive layout Electric vehicle technologies

See also

References