How to choose a used 4×4 car

Buying a used 4×4 car can be complicated, but it can also be very rewarding. 4×4, also known as all-wheel drive, offers better traction in difficult conditions such as snow, ice or rough terrain. However, choosing the right car and brand of drive can be a challenge. In this article, we will look at the key aspects you should consider when buying a used 4×4, including the advantages and disadvantages of this type of drive and the specifics of each manufacturer, such as Audi quattro or BMW xDrive. How to choose a 4×4 car?

How to choose a 4×4 car? Introduction to four-wheel drive.

4×4 means that all four wheels receive torque from the engine, which increases the vehicle's traction and stability on slippery or impassable surfaces. There are different types of 4×4 systems, from permanent systems that constantly distribute torque between the wheels, to those that are activated manually or automatically.

AWD – Permanent 4×4 drive

A four-wheel drive system, also known as AWD, constantly transfers engine power to all four wheels. This transfer is accomplished through a shaft and a set of three differentials located between and on both axles of the vehicle.

This type of drivetrain gained popularity thanks to models such as the Audi Quattro, Subaru, and the original Land Rover Defender. It is widely used in many current SUVs, including those from Mercedes, Range Rover, and Toyota Land Cruiser.

Differentials allow for an even distribution of power between the two axles in a 50:50 ratio. However, if one wheel slips, torque can be lost to the other wheels, which can trap the vehicle. The solution is to add a differential lock between the axles, which solves this problem. The lock can be activated manually or electronically. Another option is to use an interaxle differential with an added clutch, which can be viscous or electronically controlled.

Most modern vehicles no longer need a lock-up or interaxle clutch. Instead, an electronic system detects wheel slippage and brakes them, preventing torque loss to the other wheels. This advanced system can be found, for example, in new Mercedes models.

4WD – Switchable/engageable four-wheel drive

Some vehicles use a system where only one axle is primarily active, while the other axle is engaged as needed. This is usually done using a special clutch that allows power to be transferred to the secondary axle. One of the best-known examples of this system is Haldex technology. The original generation of this technology was quite crude in its function, with a noticeable interference when the rear axle is engaged. Over time, developments have occurred where modern electronics constantly monitor wheel speed and effectively respond to loss of grip, adapting to the situation before a problem arises. The distribution of power between the axles thus changes very subtly and dynamically, for example when starting off, the rear wheels are preferred for better traction.

4×4 car with viscous coupling

This text describes a basic type of all-wheel drive for cars, which is ideal for less demanding drivers and common driving situations, such as climbing hills. The key element here is a system that drives only one axle of the vehicle by default. When traction is lost, the viscosity of the oil in the system changes, which activates the clutch and thus engages the other axle. This process is automatic and does not require any electronics, which ensures the simplicity and high reliability of the system. However, this system is not manually adjustable and cannot be controlled, which has led to its gradual abandonment by some car manufacturers. Nevertheless, this type of drive is still used by some brands, such as Suzuki or Fiat Panda. Historically, this system has also been used in some models from Volkswagen and Porsche. The main disadvantages include lower efficiency, a tendency for the clutch to overheat under higher loads, and suboptimal vehicle behavior in corners.

Electric all-wheel drive

Whether you have a complete guide on how to choose a used 4×4 car, you also need to take into account the electric drive. In the current automotive industry, where hybrid and plug-in hybrid technologies are growing in popularity, there is a trend towards integrating electric motors to drive individual axles of vehicles. This approach is particularly noticeable in some SUV models from manufacturers such as Toyota and Lexus, as well as in newer plug-in hybrid models from groups such as PSA and Volvo. In basic principle, it works in such a way that the combustion engine provides drive to the front wheels, while the rear wheels are driven exclusively by an electric motor. This means that there is no mechanical connection between the axles, but the drive is coordinated by electronic systems. The vehicle thus activates the rear axle only when needed, based on a decision by the electronics, or if a specific driving mode is selected. Thanks to the absence of a cardan shaft and the combination of efficiency with better traction, this is a very efficient system. However, for the system to work properly, it is necessary that the batteries are sufficiently charged.

How to check a used 4×4 car before buying?

Inspecting a used four-wheel drive (4×4) vehicle requires specific attention and expertise, making it essential to have it performed by an experienced technician. This type of drive is technically more complex than standard two-wheel drive and can therefore hide various potential problems that are not immediately apparent.

1. Complexity of the 4×4 system: All-wheel drive involves complex components such as the transmission, transfer case, differentials and other parts of the drive system. These components can be prone to wear and damage, especially if the vehicle has been used in demanding conditions such as off-road driving.
2. Hidden problems: Without expert knowledge and proper diagnostic techniques, some problems can be overlooked. This can include excessive wear, water or mud damage, and problems with the electronic control of the 4×4.
3. Safety and reliability: A poor quality or malfunctioning all-wheel drive system can significantly affect the safety and driving characteristics of a vehicle. Undetected problems can lead to expensive repairs and can even be dangerous for the driver and other road users.
4. Vehicle value: A diagnostic performed by an experienced technician can also provide important information about the vehicle's overall condition and value, which is key when negotiating the price of a used 4x4 vehicle.
5. Long-term maintenance: A professional inspection helps identify necessary maintenance interventions and thus prevent possible future problems and expensive repairs.

Given these aspects, it is essential that potential buyers of a used four-wheel drive vehicle have a thorough inspection of the vehicle performed by experienced technicianwho has the necessary knowledge and equipment to assess the technical condition and functionality of the 4×4 system.

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