BMW G42 M240i ADRO Conversion: The Build BMW Should Have Shipped

Park a G42 M240i next to a 218i and most people walking past won't know which one has the B58. That's the problem. It's a properly quick coupe that too often looks like the sensible one, and that's exactly what this build sets out to fix.

This guide uses one Fire Red LCI M240i as the case study. It got the full ADRO aero programme, TREVORA Pre-preg Carbon Fibre on the grille and mirrors, a set of Eibach springs and Rotiform 20-inch wheels, all fitted in a single day at AUTOID as a V1 styling build. We filmed it. This page is the part the film doesn't have time for: what each piece does, how they work together, what the clearance trade-offs really are, and what we'd tell you before you order any of it.

We build and style these cars, and we sell the parts that end up on them. So here's our promise. We'll tell you what the film shows, what the product pages actually say, and where we simply don't know yet. No guessed numbers, no made-up fitment, and no pretending a G42 turns into an M2 because it's wearing a big spoiler.

The build at a glance

Before we get into the detail, here's the whole car on one table. The left column is what you'd see on the ramp. The right column is what it means if you own a G42 and want to do something similar.

What this G42 M240i conversion is trying to fix

Why the M240i reads like a 218i

The G42 has good bones. Short overhangs, a long bonnet, a proper coupe roofline and a straight-six under the bonnet in M240i form. Yet from the kerb, the M240i can look awfully close to the cheaper cars in the range. The lower bumper is fussy rather than aggressive, the sills sit high and plain, the boot lid finishes in a timid lip, and the standard 19-inch wheels leave a visible gap in the arches.

The workshop opens the film on exactly that point: these cars look the same as a 218i. The closing exchange lands on the same note: a great platform to start from, a bit too much like a 218 out of the box, and once the mods go on, it shows what it should have looked like. That's the brief in one line, and it's why this guide is about the whole car rather than one part.

The owner and the brief

This car belongs to George Baggs. It's his second G42 through our workshop. He sold the first one after about six months, having done what he could within budget, tried an X3 M, decided it wasn't for him and came back to the G42. His stated aim this time was the best G42 he could build.

We mention that for one reason. It tells you the G42 is a car people come back to, and that the lessons from the first car shaped the second. The biggest of those lessons was about splitter clearance, and you'll see it run through every decision on this build.

Scope on the day was deliberately narrow. The plan was styling only: make the car look as good as possible, then return for interior work, intakes and a louder exhaust in a later film. The stock exhaust tips stayed on for a reason, which we'll come to.

On camera, the workshop calls this ADRO body kit Europe's first. That's how it was described on the day. We haven't verified it independently, and it makes no difference to fitment, clearance planning or build order whether this car is the first G42 in Europe to wear the kit or the fiftieth.

Programme or one loud piece? ADRO versus single-piece carbon

Most G42 owners start with one part. A spoiler, usually, or a front lip. It's an understandable instinct. It's also the one that most often leaves the car looking unfinished.

Here's why. A single carbon piece draws the eye to itself, and then the eye wanders off and notices that everything else is still standard. A loud spoiler on a car with plain sills and a stock bumper doesn't say "fast coupe". It says "someone bought a spoiler". The ADRO programme on this car works because the front splitter, the side skirts, the diffuser and the duckbill all share one line and one level of aggression.

That doesn't mean single pieces are wrong. It means you should buy them knowing where they lead.

If you do start with one piece, start with the one you're least likely to regret. On a G42 that's normally the rear, because the duckbill changes the silhouette without adding any clearance risk. Starting with the most aggressive splitter and nothing else is the fastest way to get the stress without the payoff.

The ADRO package, part by part

ADRO supplies the aero on this car. TREVORA supplies the Pre-preg Carbon Fibre detail on the grille and mirrors. Springs and wheels sit in the stance chapter further down. We don't quote prices, stock or lead times on this page, because they change. Check the live product page when you order.

Front splitter

The splitter does most of the work up front. It extends the bumper's lower edge, adds shadow underneath and makes the nose look lower and wider than it is. On the film it's called very aggressive more than once, and the host reckons it takes aggressive to a new level, even compared with the TREVORA splitter.

Fitting looked straightforward. The lower part of the front bumper came off, then the splitter went on to the OEM mounting holes. The product page backs that up: it says the splitter was designed from G42 bumper data and mounts to the existing points with no cutting or drilling, with hardware included.

The catch is the one this owner learned the hard way. On his first G42, an ADRO splitter was smashed within a few days of leaving the workshop. A replacement went on and nearly cracked too. That's not a criticism of the part. It's what happens when an aggressive splitter meets a lowered car and British speed humps without a plan. If you're ordering one, read the clearance section before you choose your springs.

Live product: ADRO BMW 2 Series G42 front splitter.

Side skirts

The skirts carry the splitter's line down the side of the car. On the film the host calls them the most aggressive G42 side skirt he's seen, and notes that, in typical ADRO fashion, they use the OEM holes and mounting points.

They do the unglamorous, essential job. A G42's door panels are tall and flat, and in a bright colour like Fire Red that can make the car look taller than it is. A skirt adds a dark line along the bottom of that panel, which breaks up the side and pulls the car visually towards the ground. Without skirts, a splitter and duckbill can look like they belong to two different cars. With them, the lowered stance and 20-inch wheels read as one decision.

The product page describes them as wet carbon, supplied as a matched left and right pair with hardware. Skirts also sit closer to the road than you'd think once the car is lowered, so treat steep driveways and high kerbs with respect.

Live product: ADRO BMW 2 Series G42 side skirts.

Rear diffuser and winglets

The diffuser fills the bottom of the rear bumper and, with the winglets either side, gives the back of the car real width. On this install the diffuser and winglets went on with 3M tape and self-tappers. From a low rear three-quarter, the host says the winglets are what tie the whole aggressive look together.

The product page sells it as a complete diffuser set with all the components and hardware for a bolt-on fit to the existing rear bumper points. What it doesn't do is list winglets as a separate item in the box. The film clearly shows winglets fitted with the diffuser, so if they matter to you, ask us to confirm exactly what comes in the set before you order.

There's one more useful line on that page: the diffuser is designed around the standard G42 exhaust exit positions. That matters if you're planning a new exhaust later, which this owner is. More on that in the phase-two section.

Live product: ADRO BMW 2 Series G42 rear diffuser.

Duckbill spoiler

If one part changes the G42's silhouette, it's this. The duckbill (the film calls it a duct-tail) turns the boot lid's timid factory lip into a proper raised edge. It's aggressive without being an M2-style wing. The host jokes you could pull the car around by it. At the reveal it's the part the owner keeps coming back to.

Fitting is simple but fiddly. The OEM lip comes off with fishing wire, the old adhesive is cleaned off with a toffee (eraser) wheel, and the new spoiler goes on with 3M tape peeled back a little at a time so you can line it up before it grabs. The host notes that it more or less locates itself on the boot lid. Dry-fit it before you peel anything.

The product page lists it for both the G42 2 Series and the G87 M2, in pre-preg carbon, with 3M tape included and no drilling. Don't be put off by the M2 in the product name: it's the same part, listed for both cars.

Live product: ADRO BMW 2 Series G42 duckbill spoiler.

Materials and fixings: what you're actually fitting

Carbon isn't all the same, and neither is the way it's held on. Here's what the product pages say about construction and fixing, alongside what we saw on the day. Where the page doesn't say, we've said so rather than guessed.

Two practical points come out of that. First, the ADRO parts are a mix of pre-preg, wet carbon and unspecified carbon, so the finish won't be guaranteed identical piece to piece. Second, only the duckbill relies purely on tape. Everything else uses existing mounting points, which is good news if you ever want to return the car to standard.

TREVORA's role on this car

ADRO is the aero brand on this build. TREVORA is the detail brand. That distinction matters more than it sounds.

Mixing brands is fine when each one has a clear job. Mixing two full aero programmes on the same bumper line is how cars end up looking confused. The film is honest about that. The host says he thought the TREVORA G42 kit was aggressive, then ADRO "one-upped" it with something more extreme. Different kits, different levels of aggression, and you choose one for the aero.

TREVORA also makes its own G42 aero line. It wasn't the route taken on this car, and we wouldn't stack it on top of the ADRO parts.

Kidney grille

The LCI nose with the small M badge and the TREVORA grille is what makes the front look finished rather than half done. With the gloss black grille swapped for Pre-preg Carbon Fibre, the splitter and grille read as a pair, and on the walkaround the host calls the front end "perfection". He also points out that the little LCI M badge is how you spot a later G42 M240i on the road. That's a useful spotting tip, not a fitment guarantee.

The product page lists the grille for the G42 2 Series and M240i from 2021, and it comes with a camera cut-out piece, so it works whether or not your car has the front camera. If you're unsure about your nose or options, ask us before you order.

Mirror caps

Mirror caps are the quickest win on the car, and the film gives a genuinely useful tip. Don't remove the mirror glass. There's a high chance of breaking it. Instead, the workshop pulls the original cover off sharply in one direction so the clips release without snapping. Underneath are two small Torx bolts, both T20. Undo those, slot the indicator into the new cap and line it up, clip the corner in first, then clip the rest home.

The product page says these are a direct replacement for the OEM covers rather than a stick-on, using the same locating tabs and mounting points. It also lists them for the M240i but not the standard 220i, so check your car. UK cars need the RHD version. Don't order left-hand-drive caps for a right-hand-drive G42.

Live products: TREVORA G42 Pre-preg Carbon Fibre kidney grille and TREVORA G42 Pre-preg Carbon Fibre mirror caps RHD.

Why the parts need to read as one design

A coordinated programme does the opposite of a single loud part. Splitter edge into sill, sill into diffuser and winglets, duckbill over the top, 20-inch wheels filling the arches and carbon on the grille and mirrors. It reads as one design decision. That's the difference between buying a part and buying a direction.

The walkaround on the film follows that order, and it's a good test for your own car.

Listen to the reveal and you hear the real order of what changed. The owner goes to the spoiler first, then the wheels, then the front ride height. Silhouette, stance, then the daily worry. That's the hierarchy to plan around.

The same rule works in reverse. Don't put an ADRO diffuser under a lip from another brand and expect the rear to look intentional. Continuity is the product.

Colour, wheel finish and the Fire Red question

Colour matters more on a kit car than people admit. Fire Red is described on the film as a brand-new colour, and the host's view is that it does this kit justice. He goes as far as telling G42 buyers to consider one if a Fire Red car comes up. At the reveal it's described as making the car pop, looking "expensive, aggressive, classy".

That's opinion, not a product recommendation. But it makes a useful point. Pre-preg Carbon Fibre and dark wheels behave very differently against a strong colour than against silver or grey. Against Fire Red, the carbon and satin black wheels give the lower half of the car a dark, continuous base. Against a darker paint, the same parts would blend in more and the change would be subtler. The owner's previous G42 was black, and he says this one looks completely different.

Satin black isn't the only option, either. At the reveal, silver wheels are floated as an option that would also work. If your car is a darker colour and you want the wheels to stand out, that's worth thinking about before you commit.

Suspension and stance: the part of the build that changes daily life

This is the chapter that decides whether the ADRO programme is enjoyable every day or stressful at every speed hump.

Why 20s, not fashion alone

The car came on 19-inch wheels as standard. It left on Rotiform 20s in satin black, on Michelin tyres. The film names the wheel as a KPRS. The reasoning isn't just arch fill. After the first G42's splitters were smashed and nearly cracked, the workshop explains that the 20s would lift the car a little, and that combined with the springs this would give the new splitter a better chance. Bigger wheel, thicker tyre, as it's put on the film.

On the ramp, the tyre fitter swapped the tyre pressure sensors over from the old wheels to the new ones before the Michelins went on. Easy to forget, and worth asking about if you're having wheels fitted.

We haven't linked a wheel product on this page. We can't yet confirm the exact width, offset, load rating or tyre size used on this car, and we'd rather send you to us for that than guess. If you want this look, speak to us first.

What the film says about the springs

On the film, the springs are introduced as a brand-new Eibach kit with a manual height adjuster, "like what you'd get off a coilover", so the ride height can be wound up or down. The workshop says it's the first time they'd fitted a set. The adjuster was set to its lowest first, with the idea of winding it up if the aggressive splitter needed more room.

That's how the kit was described on the day, and it's useful context for how the workshop was thinking about clearance. We haven't confirmed the exact part number that went on this particular car, and a height-adjustable Eibach kit isn't something we list for the G42. If you want to know precisely what's on George's car, ask us and we'll check the workshop record.

The G42 spring we list and sell: Eibach Pro-Kit

For G42 owners, the Eibach kit we list and sell is the fixed Eibach Pro-Kit 20 mm lowering springs for BMW 2 Series and M240i G42. The product page states a 20 mm drop front and 20 mm rear. It lists the G42 2 Series and M240i, in both xDrive and RWD form, and says the springs are designed to work with the standard dampers. It's a fixed-drop spring with a progressive design. There's no height adjuster.

Living with a fixed drop

Plan daily life around that fixed drop. With an aggressive ADRO splitter, your clearance comes from wheel and tyre diameter, how you drive and where you take the car. It won't come from an adjuster, because the Pro-Kit doesn't have one. And don't add millimetres to the 20 mm figure or treat it as a measured result from this film. Nobody measured anything on camera.

The subjective verdict from the film, for what it's worth: after the springs and wheels went on, the host took the car for a short drive and said it was "driving unreal". At the reveal, the owner's first worry was that the front was low enough to put the splitter at risk, and the answer was the classic fist check under the nose. That's opinion and a hand under a bumper, not a ride-height sheet. The film also says the car would drop a little more after being driven in and out, which is another reason to look again once it's settled before you call the stance finished.

Stance order: wheels first, springs second, settle third

The order you do stance work in matters, because each step changes how the next one looks and feels. Here's the sequence we'd follow on a G42 carrying aggressive aero.

Clearance risks and how to manage them

Every part of this build looks better lower. Every part of it is also more exposed lower. Here's where the risk sits and what we'd do about it.

None of this is a reason not to build the car. It's the price of the look. Own the clearance tax before you own the photos.

Fitting it: what the workshop day looked like

This build went from standard to finished in a single day at the workshop, and the film gives a decent picture of the order. It isn't a step-by-step guide for your car, and we'd always follow the instructions with each part, but it shows how a workshop sequences the job.

DIY or workshop?

Some of this is well within a confident home mechanic's reach. Mirror caps are quick, and the film calls them nice and easy, provided you follow the pull-don't-pry tip. The duckbill is mostly about patience and alignment. The splitter and skirts use existing mounting points, but you'll need the car safely raised and the bumper's lower section off.

Springs are a different matter. They need the right tools, safe spring handling and an alignment afterwards. We'd always have springs fitted by a workshop. And if you're doing the whole programme in one go, the time saved by having it done together, and the benefit of judging the stance with everything fitted, is hard to beat.

Owner choices: which version of this build suits you?

Not every G42 owner wants George's car, and that's fine. Here's how we'd scale this build for different owners, using only parts on this page.

What the conversion does well, and what it can't do

Honest gaps: what we can't tell you yet

Every build guide has gaps. Here are ours, why they exist and how to close them before you spend money.

What comes next: phase two

This was a V1, and the owner was clear about that. The stock exhaust tips are still on the car on purpose. In a few weeks, the film says, he's switching to a Milltek cat-back exhaust and adding downpipes. Keeping the standard tips until then avoids buying tips twice.

That's where the diffuser choice pays off. The ADRO product page says the diffuser is designed around the standard G42 exhaust exit positions, and that most aftermarket systems with compatible tip placement will integrate cleanly. "Most" isn't "all", so check tip placement on any system against the diffuser before you order it.

Beyond the exhaust, the plan is to make the car louder, add intakes and complete the interior, with "carbon back seats" and what the owner calls "a few little spicy bits". None of that is on the car yet, so none of it is in this guide. If you're copying this approach, split your budget the same way: exterior and stance first, then sound and breathing, then the cabin.

Build-order advice for a G42 owner

Copy the thinking, not the shopping list.

1. Decide how you use the car and what clearance you can live with. This owner's history makes that step non-negotiable. If you already scrape, an aggressive ADRO splitter will remind you more often.
2. Lock wheel and tyre size before you order springs. Diameter and sidewall change how low you can comfortably live.
3. Check every ADRO and TREVORA part against your exact G42. LCI nose, bumper, front camera and the RHD mirror version all matter. Use the live links in the parts table, or ask us.
4. Choose one aero programme and stick to it. ADRO on this car. Don't mix another brand's lip or diffuser into the same line.
5. Fit the exterior using the method your kit actually uses. On this car the splitter and skirts used OEM holes, the diffuser went on with 3M tape and self-tappers, and the duckbill with tape. Check against what's in your box.
6. Fit springs with the wheels, then let the car settle. For the G42, the kit we sell is the fixed Pro-Kit, so plan splitter clearance around its 20 mm drop, not around an adjuster.
7. Get it aligned and record the stance. Photos from the same spot are worth more than memory.
8. Leave exhaust and interior as a second phase if you're following this V1. The stock tips on this car are a deliberate placeholder for a Milltek system and downpipes.

Watch the build

The full AUTOIDTV film this guide is built from is here:

Use the walkaround and reveal for the visuals. Use this page for the ordering decisions the film doesn't stop to explain.

Verdict

The lesson from this Fire Red G42 is design continuity, not brochure horsepower. An ADRO splitter, skirts, diffuser and duckbill, finished with TREVORA Pre-preg Carbon Fibre on the grille and mirrors, is a coherent answer to the M240i's lookalike problem. The right wheels and springs decide whether that answer works on British roads every day.

Own the clearance tax before you own the photos. For your G42, the spring we sell is the Eibach Pro-Kit: plan around its 20 mm drop, choose wheels with clearance in mind and check the splitter once the car has settled. And treat this V1 as the styling chapter. Sound, breathing and the interior are coming next, and that's the right order.

For the bigger picture on the G42, from buying to modification order and the chassis itself, read AUTOID's definitive G42 guide. This page is the deep dive on one build. That guide is where to start if you're still deciding which G42 to buy.