What is car body roll or lean?

When reading through car reviews you may have come across the term ‘body roll’ or ‘body lean’. This is usually mentioned when referring to a car’s ride and handling characteristics. In most instances reviewers tend to prefer less body roll, but it may not always be apparent as to why.

In this article we go into what body lean is and how it is an important consideration when looking for your next car to lease or purchase.

What exactly is body roll in a car?

Just about every car has shock absorbers and springs attached to each wheel. This allows the body to move independently of the chassis beneath it.

Assuming you are driving at legal speeds, your car’s tyres will remain in contact with the road and the lean you experience is the suspension system expanding and compressing as the weight of the car shifts during cornering.

To get a quick, practical demonstration of body roll, drive down a road with a few sharp corners. The way your car leans to one side during cornering is called body roll. If you turn left, the car will roll to the right and vice versa.

Why does body roll happen in a car?

Body roll occurs when a centrifugal force acts on a car as it goes around a corner. This force is the same thing that pushes water to the bottom of a bucket as you swing it around and sticks your clothes to the sides of a spinning washing machine.

Higher cornering speeds will result in a higher centrifugal force, causing more body lean. The suspension setup, weight, size and height of a car all play a part in how much body roll you will experience. 

Is body roll dangerous?

Not inherently. Body roll is a function of a car’s suspension system. Each manufacturer builds an element of body roll into their vehicles that most closely matches the driving characteristics they desire. There was a time, many moons ago, when body roll could overcome a car’s suspension setup and see a car roll over during sudden directional changes; this typically affected tall cars or ones with crude suspension setups but, while it is certainly possible to roll a car in extreme situations, technologies like electronic stability control have greatly reduced the chances of this occurring. 

Too much body roll will make a car feel loose and imprecise when cornering. Too little body roll will result in a bone-jarring ride and may even reduce traction levels as the wheels skip over undulations instead of remaining in contact with the road surface.

Body roll can be a useful warning that you’re approaching the car’s limits of grip. Some softly sprung cars will exhibit high levels of lean before loosing grip, while sports cars may lean only slightly due to their stiffer suspension setups. 

You may reasonably assume that extreme body roll is the precursor to actually rolling over, but this is not always the case. Some vehicles will roll quite noticeably through corners but will simply slide off the road when grip levels are exceeded. This is partly because a large portion of a car’s weight is low down (especially in EVs). Increasing your speed gradually through a corner will increase body lean but is unlikely to result in your car rolling over. Actually ending up on your roof is more likely to occur with sudden changes in velocity and direction, such as hitting a pothole or kerb at speed.

Which cars roll the most in corners?

As a general rule, taller, heavier cars will roll more than low-slung, lighter cars. Manufacturers can also influence the way a vehicle behaves around a corner by altering the suspension and shock absorber settings.

A large, heavy SUV like a Range Rover will have more roll to give it a softer ride and lots of suspension travel to allow it to traverse off-road obstacles more easily. In comparison, a Porsche Cayenne SUV will be far firmer on the road, giving it a sportier feel at the expense of some driving comfort.

Small cars with soft suspension settings can also roll quite noticeably in corners. Cars like the classic Citroen 2CV and Renault 4 would often lean comically around every bend thanks to their overly soft suspensions. This made them great over rough roads at the expense of a sharper driving feel. A modern equivalent would be the Citroen C4, it has a comfort-biased suspension setup that gives it a superbly smooth ride, but it leans more than the sportier offerings in its class.

Factors contributing to increased body roll:

• Tall bodywork and a high centre of gravity 
• Soft suspension settings
• Heavy body mass

Which cars roll the least in corners?

A light car that is low to the ground will have less weight to deal with when it goes around a corner. This will reduce the body roll, which can be further mitigated by using stiff suspension settings. Adaptive suspension and active anti-roll bars further reduce the tendency for the body to lean during cornering. 

The very first Minis in the 1950s and ‘60s had Hydrolastic suspension systems that offered reasonable ride comfort with minimal body roll. The ‘90s Citroen Xantia was one of the first production cars to have an active suspension system. It had a hydropneumatic setup that would adjust the firmness of the suspension based on your driving style.

Applying modern developments of these sorts of technologies to the latest SUVs can often deliver a sporty driving experience that belies their size and weight. Yet applying the same electronic and mechanical trickery to a low-slung, lighter car will yield even better results. As mentioned above, a Porsche Cayenne is a superlative sporty SUV, but physics dictate that a purpose-built sports car like the Porsche 911 will exhibit less body roll as it has less centrifugal force to deal with.

While this all results in a sharp and engaging driving experience, the downside is a firmer ride. And if the suspension is made too stiff the car can feel jittery and uncomfortable on all but the smoothest road surfaces.

Factors contributing to reduced body roll:

• Adaptive suspension systems
• Low-slung bodywork and a low centre of gravity
• Light body mass
• Stiff suspension settings

Should I try and stop my car rolling in corners?

You may feel that reducing your car rolling in the corners will be a beneficial move. As explained above, the handling characteristics of your car have been fine-tuned by the manufacturer to meet specific targets. Fiddling with these parameters will often upset the car’s inherent handling balance.

It is a far better idea to pick a car that suits your requirements in the first place. Most manufacturers offer a range of models that cater to different driving needs. In a very broad generalisation, brands like BMW and Audi will cater to the sportier end of the market, while Lexus and Volvo tend to have slightly softer suspensions, trading outright driving engagement for a more compliant ride.

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