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This is an installation guide for the CMST carbon-fibre kit on the 2024-onward BMW i4 (G26 Gran Coupe), covering the front lip, side skirts and rear lip. The pieces fit over the factory bumpers and sills using 3M VHB tape, panel-bonding adhesive and self-tapping screws. The i4's electric drivetrain doesn't change how the aero attaches, but it does make a couple of things worth noting: the car is heavy and low at the front, and the rear bumper carries parking sensors. Allow most of a day with two people and a hoist.

• Vehicle: BMW i4 (G26 Gran Coupe), eDrive40 / M50, 2024 onward
• Pieces covered: Front lip, side skirts, rear lip
• Fixings: 3M VHB tape, panel-bonding adhesive, self-tapping screws, factory clips
• Difficulty: Moderate; the rear lip with parking sensors needs care
• Time: Most of a day with two people

Tools and preparation

You will need a trim-removal kit, a cordless drill, fine sandpaper, degreaser, adhesion promoter, masking tape, a tape measure and a heat gun. Surface preparation is the single biggest factor in a tape-bonded kit holding for the long term: key the bonding faces of each piece with sandpaper, degrease both the parts and the car, apply adhesion promoter, and only bond when the surfaces are warm and dry, above roughly 15°C. In cooler Australian conditions, warm the car and the parts indoors before bonding.

Because the i4 is an EV with no engine bay heat at the front, there is no thermal concern for the front lip, but the car's low front splitter area means clearance matters — dry-fit the front lip and check approach angles before committing. Dry-fit the skirts and rear lip too, and mark every position with masking tape.

Difficulty and time estimate

This is a moderate install. The front lip and side skirts are standard sand, bond and screw jobs. The rear lip is the step that needs the most attention because the i4's rear bumper carries the parking-distance sensors and the reflectors, which have to be preserved. None of it is beyond a careful owner, but the long panels and the rear sensors are easier and safer with two people. Budget most of a day.

Step 1: Front lip

Key the bonding face of the front lip with sandpaper, degrease it and the lower bumper, and apply adhesion promoter where the tape and adhesive will sit. Run 3M VHB tape along the lip's mating edge with a few beads of panel-bonding adhesive alongside. Peel one end of the backing, and with a second person align the lip across the front bumper — confirm it is centred and flush at both corners — then peel the rest and press it home firmly. Fix the lower edge with self-tapping screws so the bottom of the lip is locked to the bumper while the tape and adhesive hold the top.

The i4 sits low at the nose and is a heavy car, so the front lip is the most exposed piece to kerbs and steep driveways. Set it carefully and check your daily ramps and gutters before the adhesive cures, because a front lip that catches will lift at the edge over time.

Step 2: Side skirts

The side skirts bond along the lower door sills. Key and degrease the inner bonding edge of each skirt, apply 3M tape and a few beads of panel-bonding adhesive. Peel one end of the tape, and with two people align the skirt to the door line — confirm it sits level and meets the front lip cleanly at the leading edge — then peel the rest, press home, and drive self-tapping screws underneath to fix the lower edge. Press the whole length firmly to seat the tape. Repeat on the other side using the same method, measuring so both skirts sit at the same height.

Step 3: Rear lip (the careful one)

The rear lip is the step to take slowly because of the i4's rear sensors. Remove the original rear lip and the lower bumper section together, then carefully separate the factory reflectors and note the position of the parking-distance sensors — these are preserved and transferred so the car's parking aids and reflectors keep working. Locate the CMST rear lip on the bumper's clip points and fix it with self-tapping screws, making sure it seats tight with no gap at the join. Where the lip integrates with the rear lighting or sensor wiring, reconnect to the factory colour code — red to positive, black to earth — and do not improvise. Reinstall the original fasteners and refit the lip to the car.

Before final reassembly, test the parking sensors and the rear reflectors. A mis-seated sensor can disable the i4's parking aids, so confirm they read correctly. If you are not confident working around the sensors and wiring, hand this step to a workshop.

Fitment tips and cautions

• Protect the parking sensors. Transfer them carefully into the rear lip and test the parking aids before you finish.
• Mind the low front. The i4 is heavy and low — set the front lip with daily clearance in mind to stop edges lifting.
• Match the skirts left-to-right. Measure so both sides sit at the same height and meet the front lip cleanly.
• Key and degrease every bonding face; the smooth factory bumpers need a prepared surface for the tape.
• Warm, dry conditions for the 3M VHB tape; bond indoors in cold weather.
• Cure time. Keep the car out of the rain and away from a wash while the adhesive reaches full strength.

Frequently asked questions

Does fitting a body kit affect the i4's range or warranty?

A carbon lip, skirts and rear lip are external aero pieces that bond over the factory panels, so they do not touch the high-voltage system. Any effect on range from aero changes is negligible at normal speeds. For warranty, fit the kit so it is reversible and check your dealer's position on cosmetic modifications.

Will the parking sensors still work after fitting the rear lip?

Yes, provided the factory sensors are transferred into the CMST rear lip and the wiring is reconnected to factory positions. If a sensor is seated incorrectly the parking aids can fault, so test them before final reassembly.

Is the front lip going to scrape on driveways?

The i4 sits low at the nose, so the front lip is the most exposed piece. Set it carefully and check your regular ramps and gutters. Taking driveways at an angle and keeping an eye on steep entries will keep the lip's edge intact.

Do these pieces fit the eDrive40 and the M50?

The kit is designed for the 2024-onward i4 G26 Gran Coupe. Confirm whether your car has the standard or M Sport rear bumper when ordering, as that affects the rear lip's fit.

Should I have it professionally fitted?

For a clean result on the rear lip and its sensors, professional fitment is worth considering. AME Motorsport can arrange installation in Australia so the sensor transfer, the long bonded edges and the alignment are done correctly.

Get it fitted in Australia

Prefer a professional install? AME Motorsport can help. Browse the full i4 range in the CMST body kits for BMW, choose a carbon nose from the CMST front lip collection, add matching sills from the CMST side skirts range, and explore the wider CMST catalogue. Contact us to book fitment or for current i4 pricing.