Wide Body Kits — Everything You Need to Know Before Buying

A wide body kit is the most transformative modification you can make to a performance car. Nothing else changes a vehicle's visual presence as dramatically — a well-executed wide body conversion takes a recognisable production car and turns it into something that looks genuinely purpose-built for competition. Done correctly, the result is extraordinary. Done poorly, it's immediately and irreversibly obvious.

This guide covers everything you need to know before committing to a wide body kit — what they are, how they work, what they cost in reality, how to choose the right one, and what the installation process actually involves. If you're considering a wide body conversion for your BMW, McLaren, Ferrari, Lamborghini, or Porsche, read this before you spend a penny.

What Is a Wide Body Kit?

A wide body kit is a collection of body panels and arch extensions that increase the overall width of a vehicle beyond its factory dimensions. At its most basic level this means wider front and rear arches — either bolt-on extensions that attach to the existing arches or full replacement panels that are bonded or welded in place. A complete wide body kit will typically also include a revised front bumper, wider side skirts, a revised rear bumper, and a rear diffuser — all designed to integrate the wider arches into the car's overall visual language cohesively.

The purpose of a wide body conversion is twofold. Visually, it gives the car a more aggressive, planted stance and allows wider wheels and tyres to be fitted without the arches fouling the bodywork. Functionally, wider track width improves cornering stability and allows significantly more rubber to be put on the road — both of which have genuine performance benefits on track.

Types of Wide Body Kit

Not all wide body kits are the same, and understanding the different construction approaches is important before choosing one.

Bolt-on arch extensions are the most accessible type of wide body conversion. These are panels that attach to the outside of the existing arches using bolts, rivets, or adhesive — adding width without requiring permanent modification to the underlying bodywork. The advantage is reversibility — in theory the car can be returned to standard. The disadvantage is that poorly designed bolt-on arches often look exactly like what they are — panels stuck to the outside of a standard arch — rather than a cohesive redesign of the car's body.

Full replacement wide body panels are the more committed approach. These replace the factory arch sections entirely, requiring cutting of the existing bodywork and professional installation. The result, when done correctly, looks factory — as though the car was built this way from the outset. This is the approach used on the highest quality wide body kits and the one that produces the most convincing results. It is also the most expensive and the least reversible.

Overfender kits sit somewhere between the two — larger bolt-on arch extensions that cover a significant portion of the existing bodywork and create the appearance of a full wide body conversion while retaining the original panels beneath. Popular on Japanese performance cars and increasingly on European models, overfenders are a good middle ground for owners who want dramatic width gains without permanently modifying their car.

How Much Width Does a Wide Body Kit Add?

This varies significantly by kit. Entry-level wide body conversions typically add 20–40mm of width per side across the front and rear arches. Mid-range kits add 40–60mm per side. The most aggressive wide body conversions — designed for full racing builds or show cars — can add 80mm or more per side, creating a stance that is dramatically wider than the factory car.

The width addition determines what wheel and tyre sizes are possible — and this is a critical consideration. A wide body kit that adds 50mm per side per axle allows a wheel and tyre combination that is 100mm wider in total across that axle than standard. This needs to be planned carefully in conjunction with wheel offset and suspension geometry to ensure the tyres actually fill the arches correctly and the car handles predictably.

What a Wide Body Kit Actually Costs

This is where many buyers get a surprise. The price of the kit itself is only one part of the total investment. A realistic wide body build budget needs to account for the following.

The kit itself — depending on material, manufacturer, and complexity, a quality wide body kit for a BMW M car, McLaren, Ferrari, Lamborghini, or Porsche will range from a few thousand pounds for a simpler bolt-on conversion to significantly more for a full replacement panel kit in dry carbon fiber.

Professional installation — a wide body kit cannot be fitted at home. It requires a bodyshop with experience in panel fitting, body modification, and paint matching. Installation costs vary by region and by the complexity of the specific kit, but should be budgeted as a significant proportion of the total project cost — in many cases as much as the kit itself.

Paint matching — every new panel needs to be painted to match your car's colour. Modern automotive paint matching is excellent but not perfect, particularly on older vehicles where the factory paint has aged. Factor in a full car respray if colour consistency is important to you.

New wheels and tyres — a wide body conversion almost always requires wider wheels and tyres to fill the arches correctly. A car with wide arches and standard-width wheels looks wrong immediately. Budget for a new wheel and tyre set as part of the project.

Suspension adjustment — wider track width changes the car's suspension geometry. A professional alignment and in most cases some geometry adjustment is required after a wide body installation to ensure the car handles correctly and wears tyres evenly.

Choosing the Right Wide Body Kit for Your Car

The most important quality criterion for any wide body kit is how well it integrates with the factory design language of the car it's fitted to. The best wide body kits look like variants the manufacturer could have built themselves — wider, more aggressive, but coherent with the car's original design intent. The worst look like aftermarket panels bolted to a standard car.

When evaluating a wide body kit for your specific vehicle, look at how the arch extensions transition into the existing bodywork. Do the lines flow naturally or do they create awkward junctions? Does the wider stance look proportionally correct from every angle? Are the front and rear arch widths balanced with each other and with the rest of the car's proportions?

Material quality matters too. Carbon fiber wide body panels are the premium choice — lightweight, strong, and visually distinctive. Fiberglass panels are more affordable but heavier and more susceptible to cracking under impact. Polyurethane panels are flexible and resistant to minor impacts, making them practical for road cars but less prestigious than carbon.

Wide Body Kits for Specific Models

Wide body conversions are available for most of the vehicles in our catalog. BMW M cars — particularly the G80 M3, G82 M4, F80 M3, and F82 M4 — have a well-developed wide body aftermarket with options ranging from subtle bolt-on arch extensions to full GT3-inspired conversions. McLaren wide body kits respect the complex aero architecture of the 570S, 720S, and Artura. Lamborghini Huracan and Aventador wide body options frequently take inspiration from the GT3 and SVJ racing variants. Ferrari 458 wide body kits follow the 458 GT3 Challenge car's proportions. Porsche 992 and 718 wide body conversions draw on the marque's own GT3 and Cup Car heritage.

In every case the best results come from kits that reference the motorsport versions of these cars — because the manufacturers themselves have already done the work of imagining what their cars look like at maximum width.

The Installation Process — What to Expect

A professional wide body installation typically takes between one and three weeks depending on the complexity of the kit and the workload of the bodyshop. The process involves removing the existing arches and surrounding panels, fitting and aligning the new wide body components, modifying the underlying body structure where required for full replacement kits, preparing all surfaces for paint, painting and lacquering, and finally reassembling the car with the new wheel and tyre combination.

Choose your bodyshop carefully. Not all bodyshops have experience with wide body conversions on high-value performance cars. Ask to see previous work, specifically on cars of similar complexity to yours. A bodyshop that has never fitted a wide body kit to a McLaren or a Lamborghini is not the right choice for your car regardless of how good their standard repair work is.

Is a Wide Body Kit Right for Your Build?

A wide body conversion is a committed decision. It changes the car permanently in most cases, requires a significant total investment, and shifts the car's identity fundamentally. It is the right choice for owners who have a clear vision of where their build is going and who are committed to executing it properly from start to finish.

It is not the right choice for owners who want a dramatic visual upgrade without the commitment — for those builds, a comprehensive aero package of splitter, side skirts, diffuser, and rear wing delivers significant visual transformation at a fraction of the cost and complexity, and with complete reversibility.

At Velocity Car Parts we stock wide body components and aero parts for BMW, McLaren, Ferrari, Lamborghini, and Porsche — all verified for model-specific fitment and backed by our fitment guarantee. Browse our full range at velocitycarparts.shop and build with confidence.