The Short Answer
Side skirts for the BMW G42 M240i run from £149 to £1,499. Gloss black ABS winglets start at £149 and full-length ABS skirts at £199. Carbon fibre full-length skirts sit between £499 and £1,115 depending on maker and lay-up, with genuine BMW M Performance carbon blades at £1,499.
Across the four full-length options in the G42 range, the average is £615. Budget for fitting on top.
The G42 sits high, side skirts fix that.
The M240i leaves the factory with a lot of visual air along its flank. The sill is soft, the arch gap is generous, and from three-quarters the car reads taller than it is. Side skirts are the cheapest way to correct that, because they work on the line your eye follows most.
They are also the part most people get wrong on price. Two skirts can look near identical in a listing and be separated by £900. The difference is rarely the shape. It is the material, the lay-up and who engineered the fit.
An important choice to make.
Before material, decide how much of the sill you want to change. That single choice moves the price more than anything else.
Blades and winglets: £149 to £1,499
Bolt to the lower edge of the factory sill. Adds a shadow line and a little width without changing the profile. The reversible option, and the one that suits a daily.
Full-length skirts: £199 to £1,115
Run arch to arch and rewrite the whole side of the car. Bigger visual drop, more surface to keep clean, more to catch on a kerb. This is the one that makes the car look lowered before it is.
Skirts inside a kit: £349 to £4,699
Bought with a splitter, diffuser and often a spoiler. Cheaper per part and visually coherent, but you commit to one design language in a single go.
What each material costs, and why
Four tiers, and the jumps between them are honest ones. You are paying for tooling, cure process and finish stability, in that order.
| Material | What you are buying | G42 price |
|---|---|---|
| Gloss black ABS | Injection or vacuum-formed plastic in a factory-match gloss. Flexible, forgiving of a kerb, and repairable. The finish is the limit: it will haze before carbon will. | £149 – £199 |
| Carbon over composite | A carbon skin over a moulded substrate, UV-stable clearcoat on top. Real weave, real depth, at a fraction of a full autoclave part. The sensible middle for a road car. | £499 |
| Full pre-preg carbon | Pre-impregnated cloth, autoclave-cured. Lighter, stiffer, consistent weave alignment through the corners where cheap parts go crooked. Priced on process, not looks. | £479 – £1,115 |
| Genuine M Performance | BMW's own carbon blades, clearcoat sealed, with the part number and the dealer paperwork. You are paying for provenance and residual value as much as material. | £1,499 |
Every G42 side skirt option, priced
The current range for the 2 Series and M240i G42, lowest to highest.
| Part | Maker and material | Price |
|---|---|---|
| Gloss Black Side Blade Winglets | FORM Industries · ABS | £149 |
| Gloss Black Full Length Side Skirts | FORM Industries · ABS | £199 |
| Pre-preg Carbon Fibre Side Blade Winglets | TRE by FORM · Pre-preg carbon | £479 |
| Carbon Fibre Full Length Side Skirts | FORM Industries · Carbon fibre | £499 |
| ID-01 Full Length Side Skirts | TREVORA · Full carbon | £649 |
| Carbon Fibre Side Skirts | ADRO · Carbon fibre | £1,115 |
| Genuine Carbon Fibre Side Skirt Blades | BMW M Performance · Carbon fibre | £1,499 |
Some essential add-ons
Almost nobody stops at skirts. Once the side of the car is resolved, the front and rear start to look untouched. Plan for it now rather than discovering it in three months.
| Add-on | Note | Price |
|---|---|---|
| Front splitter, gloss black ABS | Matches the ABS skirts exactly. The natural pairing. | £199 |
| Splitter and skirt pack, gloss black | Both parts together. Saves £49 against buying them separately. | £349 |
| Front splitter, carbon fibre by ADRO | Pairs with the ADRO skirts as a designed set. | £1,099 |
| TR87 pre-preg carbon rear wing by TREVORA | The loudest thing on this list. Not a subtle addition. | £1,679 |
| TREVORA ID-01 full carbon body kit | Skirts, splitter and rear elements as one coherent design. | £2,199 |
| Genuine M Performance full carbon kit | Every carbon part BMW makes for the car, blades included. | £4,699 |
Fitting is the line people forget. Skirts are 3M tape and clip work rather than drilling, so a competent installer will have both sides on in two to three hours. Budget accordingly, and factor in a full kit taking most of a day.
One honest note on clearance
A full-length skirt sits lower than the factory sill by design. On a G42 that is already on springs or coilovers, that is the difference between clearing a speed bump and hearing it. Approach at an angle, and be honest with yourself about the car parks you use.
So what should you spend?
If the car is a daily and you want the sill tightened without commitment, £149 to £199 in gloss black does more than the price suggests. It matches the factory shadow gap and nothing about it is permanent.
If the car already has wheels and a drop, the £499 to £649 carbon bracket is where the money starts working. Weave depth reads at a distance, and it holds up under UV in a way cheaper carbon does not.
Above that you are buying provenance, design authorship, or both. Worth it if the rest of the build has already earned it. Premature if the car is otherwise standard.
Browse the full BMW G42 styling range. Prices correct September 2026.
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