Modified BMW G82 M4: ADRO V1 Front End, TREVORA PR-1 Side Skirts and a Stage 2 Tune

Last updated: 13 October 2026

When this G82 M4 rolled into our workshop, it didn't look like a car with an S58 straight-six under the bonnet. It had a mismatched front bumper, kerbed wheels and carbon that had seen better days. The owner wanted it fixed properly, and he wanted it done fast, because the car was booked in for tuning the very next day.

So the team had one day. In that day the car got a full ADRO V1 front end, TREVORA PR-1 side skirts, Eibach SportlinePlus height-adjustable springs, Bimecc spacers and a plug-and-play exhaust valve controller. The next morning it went to Velocity Tuning for an ECU unlock, a remap and a gearbox map. A bit later the wheels came back from our paint shop in gloss black.

This is the story of how that BMW M4 was modified, part by part: what went on, why, how it was fitted, and what you need to know if you want to do the same to your own G82. Where the film shows exactly what was fitted, we say so. Where it doesn't, we tell you how to choose rather than guess.

• Car: BMW M4 Coupe (G82), rear-wheel drive
• State on arrival: mismatched front bumper, kerbed wheels, a poor previous install hiding behind the bumper
• Brief: fix it properly, then make it look and drive the way an M4 should
• Parts: seven catalogue parts, plus a remap, a gearbox map and a wheel refurb
• Time: one day in the workshop, then a day at Velocity Tuning

The build at a glance

What was wrong with it

The first job was the obvious one: take the old front bumper off. What was behind it was the most useful five minutes of the whole film, because it is exactly what a cheap job looks like once you lift the lid.

Parts had been screwed through the bumper into the grille, and the screws had all gone rusty. The parking sensors had been superglued into place. A wire at the back of the grille was held on with loose electrical tape. Casper, who took the bumper off, didn't hold back: "This is what happens when you either buy non-genuine products or take it to be installed by someone who doesn't really know what they're doing."

His advice was simple. Be wary of non-genuine parts and of shops that don't know these cars, because "this could be how yours ends up looking."

None of this was visible from the outside. The car just looked a bit off: a front bumper that didn't match the rest of the car, wheels with kerb damage and a stance that left the wheels sitting deep in the arches. That is the point. A bad fit hides until something fails, and then it costs twice.

Buying a G80 or G82 that's already modified

If you are buying a used G80 or G82 that has already been modified, this car is the one to remember. From the outside it looked like a modified M4 with a few rough edges. Behind the bumper it was a bodge. Ask who fitted the parts, ask what the parts are, and if the answers are vague, have a look before you trust it.

None of that means a modified car is a bad buy. A car modified properly, with genuine parts and receipts, can be a better buy than a standard one. It just means you should check.

The brief: fix it, then finish it

The owner didn't want a show car. He wanted his M4 to look like it should have looked all along, with the front end sorted, the stance fixed and the car sounding and driving like a proper M car. The film's title puts it as the G82 M4 BMW should have made, and that's a fair description of the brief.

That set the shopping list. One complete front end from one maker, so every part was designed to fit with the next. Side skirts that pick up the lines of that front end. Springs that drop the car without changing the dampers. Spacers to bring the wheels out to the arches. Then the software to match.

If you want the general logic for where to start on these cars, our first five mods for the G80 M3 and G82 M4 covers it. This post is what happens when you do most of that list in one day, on a car that needed rescuing first.

How the G82 M4 was modified, in order

The order matters on a one-day job. The team did it like this:

1. Old front bumper off, and the parts worth keeping transferred to the new ADRO V1 bumper.
2. Parking sensor mounts bonded to the new bumper, then left to set.
3. While the bonding set, the team got on with other jobs on the car.
4. The new bumper, with its grilles and ducts, went on, followed by the splitter.
5. Rear springs in, then the fronts.
6. Wheels off to be refurbished.
7. Valve controller fitted while the car was still in the air.
8. TREVORA PR-1 side skirts fitted.
9. Spacers fitted once the wheels came back.
10. The next morning, off to Velocity Tuning.

The trick is step three. Bonding takes time to cure, so rather than stand and wait, the team moved on to other jobs on the car and came back to the bumper once it had set. On any job that involves adhesive, plan the order around the cure time.

The ADRO M4 front end (V1)

ADRO's front end is the biggest single change on this car, and it's three separate purchases that are designed to work together: the V1 bumper, the carbon splitter for the V1 bumper, and the carbon grille and ducts for the V1 bumper. You can browse the rest of the range in our ADRO collection.

The ADRO V1 front bumper

The ADRO V1 front bumper is a complete replacement for the factory bumper. It's made from TPO, a tough, slightly flexible plastic that copes with knocks better than a rigid part would. It changes the proportions of the front of the car and gives it a much more aggressive face than the factory design.

In the box you get the bumper, a set of front grilles, a mesh backing, 3M tape and an installation kit. The splitter isn't included, which catches people out, so budget for it separately if you want the full look. The bumper is listed for the G80 M3 Saloon, G81 M3 Touring, G82 M4 Coupe and G83 M4 Convertible, both pre-LCI and LCI.

One thing to plan for: there's no colour or finish option on the listing. The bumper is supplied as it comes. If you want it in your body colour, speak to your bodyshop about preparing and painting it before it goes on.

Why a TPO bumper?

People sometimes expect a bumper like this to be carbon or fibreglass. It isn't, and for a bumper that's a good thing. TPO (thermoplastic polyolefin) is the same family of material that most car makers use for their own bumpers. It flexes a little under a knock and goes back to shape, where a rigid fibreglass bumper is more likely to crack. It also takes paint well once it's properly prepped, which matters if you want it colour-coded.

The carbon on this car's front end comes from the parts you bolt to the bumper: the splitter, the grille and the ducts. That's a sensible split. The big panel that takes the knocks is tough and flexible, and the carbon sits where you see it.

Fitting the bumper

Casper's process was straightforward. Remove the factory bumper. Transfer everything you're keeping from the old bumper to the new one. On this car that meant the centre bracket, the corner grilles, then the centre grille clipped in, then the remaining trims.

The one step you can't rush is the parking sensors. Their mounts are bonded to the new bumper, and the bonding has to set before you carry on. Fit the bumper too early and the sensors can move, which is how you end up with warning lights or sensors that point at the floor. Once it had set, the bumper went on, followed by the splitter.

The ADRO carbon splitter for the V1 bumper

The ADRO carbon splitter for the V1 bumper adds a lower lip to the V1 bumper, which is what gives the car that low, planted look from the front. It's wet carbon fibre and comes with 3M tape and installation screws.

Read this bit twice: it's made for the ADRO V1 bumper only. It won't fit the factory bumper and it won't fit the ADRO V2 bumper. If you don't have the V1 bumper, this splitter isn't for you. The splitter is built to order, so check the lead time on the product page before you book a fitting date.

ADRO carbon grille and ducts

The ADRO carbon grille and ducts replace the grille and side ducts that come with the bumper. They're pre-preg carbon fibre, made the same way as the rest of ADRO's G8X carbon. There's one product page with two options, front grille only or front ducts only, so if you want both, as on this car, order both options.

Again, these are for the ADRO V1 bumper only. They won't fit the factory bumper or the ADRO V2 bumper. At the reveal, the verdict on the front was simple: "the carbon looks insane on the front end."

V1 or V2?

ADRO now makes a newer V2 bumper as well, and it's a different design with its own matching parts. This car runs the V1 bumper, and everything in this build list is the V1 version. If you're still deciding which front end you want, our ADRO V2 front bumper post covers the other one. Just don't mix the parts: V1 accessories belong on a V1 bumper.

Wet carbon and pre-preg carbon: what's the difference?

This build has both, so it's worth explaining. The film's description calls the splitter pre-preg, but the product page is clear that it's wet carbon fibre. That's not a bad thing. It's just a different way of making carbon parts.

For a splitter that lives low down at the front of the car, wet carbon is a sensible material. For the parts at eye level, such as the grille, the ducts and the skirts, the pre-preg finish is what you notice.

Stance: Eibach SportlinePlus height-adjustable springs

When this car arrived, the wheels sat tucked inside the arches with a big gap above the tyre. Lowering springs are the quickest way to sort that without replacing the dampers, and on this car the choice was Eibach SportlinePlus height-adjustable springs.

What makes SportlinePlus different from a normal lowering spring is the rear. The rear springs come with a replacement top cup that lets you set the height, steplessly, within a range. The fronts are a fixed drop. As the team explained in the film, a height-adjustable spring is "pretty much just like a non height adjustable one", except for that top cup. If you don't want it too low, you wind the cup out. If you want it as low as it goes, you wind it all the way before you fit it. There's a tool in the kit for adjusting it.

Drop figures are Eibach's, from the product page. The springs work with the factory dampers, whether they're standard or adaptive, so you don't need to replace anything else. Eibach also says the rear spring ends are designed to reduce contact corrosion, and the springs have a polymer coating to protect them.

Adjustable or fixed springs?

On the G80 M3 we modified for Ross, we used fixed-height lowering springs. On this G82 we went height-adjustable at the rear. Neither is better in every case. It depends on what you want from the car.

On the G82 the factory rear can sit higher than you want once the front is lowered, so being able to set the rear separately is useful. Set it, drive it for a week, and adjust it if you need to.

Fitting the rear springs

The rear is the easy end of a G82, especially on a rear-wheel drive car like this one. The steps from the film:

1. Remove the rear level sensor. It's a 9 mm and a 10 mm spanner job.
2. Before you undo the bolt at the hub, mark its position. That keeps your alignment where it was when it goes back together.
3. Undo the shock bolt (18 mm).
4. Drop the arm, swap the spring and refit in reverse order.
5. When you tighten up, line up your marks and hold it there while you tighten. If you don't, your alignment will be all over the place once the car is back on the floor.
6. Refit the level sensor.

The level sensor is on the passenger side only, so the other side is just the two bolts. Even with the marks lined up, we'd always recommend a full alignment check after lowering a car.

Fitting the front springs on a rear-wheel drive G82

Without front driveshafts in the way, the front is simple on a rear-wheel drive car. Unclip the damper connector and the drop link lines from their bracket. Support the hub with a jack so it doesn't drop. Undo the top mount, take the strut out of the side of the car, swap the spring and refit it all in reverse order. The same rule applies on the front: the level sensor is only on the passenger side, so undo it before you drop the hub, or you risk snapping it.

If your M4 is xDrive, the front driveshafts make the job more involved. Our G80 M3 build shows the xDrive version of the same job.

Wheel position: Bimecc spacers

Lowering a G82 sorts the gap above the tyre, but the wheels still sit inside the arches. The fix is a set of Bimecc hub-centric wheel spacers, which bring the wheels out towards the arch line. On this car they went on last, once the refurbished wheels were back.

The film doesn't say which sizes went on this car, so we won't guess. Here's how to choose for yours, using Bimecc's own guide:

Bimecc also makes 10 mm and 20 mm spacers in the same kit, and you can mix front and rear sizes. Be honest with yourself about your tyres and how low you've gone. Some owners on different tyres have reported rubbing at the front with 15 mm all round. On a lowered car, the smaller size is the safer bet.

What's in the kit: four hub-centric spacers in 5x112 with a 66.6 mm centre bore, plus extended black bolts (60-degree taper seat, M14 x 1.25). With the locking bolt option you get 16 extended bolts, four locking bolts and a key. Without it, you get 20 extended bolts. Bimecc makes the spacers under TÜV ISO 9001 and IATF certification, but they're not TÜV certified per vehicle, which some European countries require for modified cars. If you're outside the UK, check your local rules.

The sound: a plug-and-play valve controller

While the car was in the air and waiting for its wheels, the team fitted a Milltek valve controller. It's the same type of plug-and-play valve controller we sell from Milltek Sport, which lists the G82 M4 and works with both the factory exhaust and Milltek exhausts.

The idea is simple. The G82's exhaust has electronically controlled valves. The controller sits between the car and those valves so you can choose when they're open, with a remote.

Fitting, as shown in the film:

• There's a control box and four plugs, one for each of the factory valve connectors.
• Unplug each factory valve, plug the controller's lead into it, and plug the factory connector into the controller. It's a piggyback, so nothing is cut.
• Tuck the wiring up behind the heat shields so it doesn't melt once the exhaust is hot.
• Hide the box where it can't flap about. On G series cars, the team cable-ties it to the subframe so it stays put.

The team's understanding is that the factory valves never open all the way on their own, and with the controller they open fully. It's one of the cheapest ways to change how a G82 sounds, and if you change your mind, it unplugs.

Side profile: TREVORA PR-1 side skirts

The last parts to go on were the TREVORA PR-1 side skirts for the G82 and G83. They're pre-preg carbon fibre with a dry 2x2 weave, and they carry the low line of the new front end down the side of the car. They're part of the wider PR-1 range, and our post on the TREVORA PR-1 carbon kit for the G80 M3 and G82 M4 covers the side skirts alongside the rest of the kit.

They mount to the factory mounting points, so there's no drilling into the body. The one catch on G series cars is the little push clips along the sill. You have to pop them out to fit the skirts, and you can't reuse them because they break. Order new clips, or do what our technician does: "I personally recommend getting some rivets and riveting it in." That way the skirt is solid and won't come off, and you can still drill the rivets out if you ever want to remove the skirts.

The process from the film: remove all the push clips along the sill, offer up the side skirt, then rivet it in. Passenger side first, driver side second. The PR-1 skirts are on pre-order, so check the lead time on the product page before you book the job.

A quick fitment note: these skirts are for the G82 M4 Coupe and G83 M4 Convertible, pre-LCI and LCI. The G80 M3 and G81 Touring have different sills and their own PR-1 side skirts for the G80 and G81.

Wheels: a gloss black refurb

The wheels went off to be refurbished as soon as the springs were in. They had kerb damage all the way round, and nothing ruins a lowered car faster than tatty wheels sitting closer to the arches. They came back from our paint shop in gloss black.

It sounds like a small job, but it ties the whole car together. With a red body, black wheels and black carbon at the front and sides, the car has one clear black and red theme. As the team put it on camera, "It just looks stupidly aggressive."

If your wheels are kerbed, it's worth refurbishing them at the same time as you fit spacers. The spacers push the wheels out where everyone can see them, so any damage becomes more obvious, not less.

Velocity Tuning: unlock, remap and gearbox map

The day after the workshop job, the car went to Velocity Tuning, our tuning partner, at Tommy's new unit. Tommy knows the S58 engine inside out, and if you follow the G80 scene you've probably seen his single-turbo G80 online.

The car went to Velocity with a downpipe and midpipe fitted, and Velocity's baseline run found it was already running M2 CS software. From there the plan was: unlock the ECU, tune it, then map the gearbox.

We're not printing a power figure here. The film shows Velocity's dyno numbers on camera, and you can watch them for yourself, but we'd rather you see them in context than read them out of it. Every car is different, and the right figure for your car is the one your tuner measures.

Why map the gearbox too?

This was the most useful part of the visit. Tommy's explanation was clear. The engine and gearbox talk to each other all the time, and a standard gearbox shifts in a way that's tuned for a standard engine. Make the engine much stronger and the gearbox "can actually be quite delayed in its shifting".

Mapping the gearbox does two things. It stops the gearbox holding the engine back, so it can use more of its torque. And it makes the car "a lot more punchy and fast through the gears".

There's a mechanical reason too. A gearbox map increases the pressure on the clutches. Without enough pressure, the clutches can start to slip when there's a lot more power going through them, and the longer a gear change takes, the longer they slip and the more heat they make. With quicker shifts and more pressure, Tommy said, "you actually reduce the wear quite a lot."

Tuning is specialist work, and it can affect your manufacturer's warranty. Speak to your tuner about your car before you book it in.

The reveal

The owner hadn't seen the car since he dropped it off. He waited in our waiting area, came through with his eyes shut, got spun round to face the car, and opened them.

Once he'd got over the shock, his verdict was short: "It's a different car."

The front end got the most attention, and the carbon in particular, and he was just as happy with how the whole car had come out. Then he heard it start. With the valves open after the tune, it's loud. Very loud. His verdict on the front, once he'd walked round it: "The front end's naughty."

Then the obvious thing happened. The car went straight out into London to make some noise.

What we didn't do, on purpose

A build list is just as much about what you leave off. On this car:

• No new rear aero. The rear was left as the owner already had it. The front and sides were where the problems were.
• No coilovers. SportlinePlus springs on the factory dampers give a proper drop and an adjustable rear without changing how the adaptive dampers work.
• No wheel swap. The factory wheels were fine underneath the damage, so a refurb in gloss black made more sense than new wheels.
• No mixing of front-end brands. One ADRO front end, designed as one package, rather than a splitter from one maker and a bumper from another.

If you want to see a G82 that went the other way, with ADRO at the rear as well and a full exhaust, look at the Anglesey Green G82 in our Ireland-to-Essex build. It's a very different car built around a different brief.

The full G82 M4 build list

Everything else on the car, including the tune, the gearbox map, the downpipe and midpipe and the wheel refurb, came from Velocity Tuning or our paint shop. You'll find the rest of what we offer for the car in our G82 and G83 M4 range and our G82 M4 styling and body kit collection.

Will these parts fit my G80, G81, G82 or G83?

The G80 M3 and G82 M4 share a lot, but not everything. Here's what the product pages say:

Pre-LCI and LCI cars are both covered where the product page lists them. If you're not sure which version your car is, send us your registration or VIN and we'll check.

DIY or workshop?

How reversible is this build?

If your car is on finance or a lease, read our guide to modifying a lease car and keeping mods reversible first.

Before you order: the choices that catch people out

• V1 or V2. The splitter, grille and ducts in this build are V1 only. Decide on the bumper first and buy accessories to match.
• The splitter isn't in the bumper box. Order it separately.
• Grille and ducts are two options on one page. If you want both, add both.
• Painting. The V1 bumper has no finish option. Book your bodyshop in advance if you want it colour-coded.
• Lead times. Some parts in this build are built to order or on pre-order. Check each product page before you book a fitting slot, so the car isn't off the road waiting for one part.
• Spacer sizes. Choose for your tyres and ride height, not for a photo.
• Spring direction. SportlinePlus adjusts at the rear only. Set the rear height before fitting, then fine-tune.
• Your gearbox. If you're tuning, ask about a gearbox map at the same time.

How we'd stage this build on your G82

You don't have to do it all in one day. If you want to spread it out, this is the order we'd suggest:

Living with it

We can't tell you how this car will age. It's a customer car and it has just been finished. What we can tell you is what to expect from the parts based on how they're made and fitted:

• Ride height. SportlinePlus is a moderate drop on factory dampers, so ramps and speed bumps need more care than standard, but the car stays usable. If you find it too low, wind the rears up.
• Splitter. Any splitter sits closer to the ground. Approach steep driveways at an angle.
• Carbon care. Wash carbon like paint, with a pH-neutral shampoo and a soft mitt. A coat of sealant or ceramic protection helps keep the finish deep.
• Spacers. Re-check the wheel bolt torque after the first few hundred miles.
• Valve controller. Remember which mode you left it in before a cold start at 6am.

What it cost

We don't list prices in our build stories, as they change. For current prices, see each product page in the build list above.

Watch the build

The full film is embedded at the top of this post. It shows the bumper transfer, the spring fitting, the valve controller, the side skirts, the visit to Velocity Tuning and the reveal. If you're planning a similar build, the spring section and the bumper transfer are worth watching before you start.

The AUTOID take

This car is a good example of why we push genuine parts and proper fitting. The owner's M4 had already been modified once, badly. What it needed wasn't more parts. It needed the right parts, designed to go together and fitted properly.

The ADRO V1 front end does the heavy lifting on looks. TREVORA's PR-1 skirts finish the side. Eibach's SportlinePlus springs and Bimecc spacers fix the stance without touching the dampers. The valve controller and Velocity's software sort the sound and the drive. And a gloss black refurb ties it all together.

If you want something similar for your G82, browse our G82 and G83 M4 range or get in touch with the team. And if you've got a G80 instead, see how we modified a G80 M3 as a surprise with TREVORA's PR-1 kit.