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The real cost to modify your car

What's the real cost to modify your car? I dive into my own M3 and break it down, along with providing some tips to change your own ride.


Welcome back to the mailbag, where a young reader asks how much it costs to modify your car (like my M3). If you have a question, you can email me, and I might just pick it.


Hi Mike–

I’m a 16 years (sic) old car enthusiast, and I saved up enough to get a Scion FR-S as my first car.

I want to modify it, but everything is really expensive, and I don’t want to put on cheap parts. Is it ok to put on parts from brands I’ve never heard of? Have you always modded your cars? What did the M3 cost? Seems like modded cars aren’t worth a lot more than stock ones.


– Kerry


We’ve come a long way.

Last year, I wrote an article about the myth of modifying your car, and what I wrote is still true. Yet, I ignored my own advice and turned my car into the M3 it should have been from the factory. No regrets.

Modifying a car is like having a child. It makes absolutely zero financial sense, and the return on your investment is something intangible. But we do it anyway, and if you have to ask why, you’re either not a car enthusiast, or a parent. So no Kerry, I’m not going to dissuade you from doing so.

But I will present the financial facts.

And yes, I’ve always modified my cars. From the 3000GT, the 350Z (both), even the Stinger. Ironically, the car kept closest to stock was my E92.

How much did it cost to modify my G80 M3?

As it currently sits.

Before I tell you this number, I’m going to add a disclaimer about the cost of labor. What every shop charges is their own prerogative, and I’m not going to put to pixels what all my shops cost. Suffice to say, you can double the parts cost as an estimate, then go up from there. Some of these I installed myself, but I’m not coming over to help you for pizza and beer, sorry.

Now, to make it easier to read, I’ll break it out into four categories; exterior, interior, engine bay, and performance.


M3 exterior
The car now has almost all carbon fiber in place of the black gloss trim.
  • Carbon fiber air ducts – $624
  • CSL front lip – $799
  • CF side skirts – $1,099
  • CF high-kick spoiler – $349
  • CF Upper diffuser trim – $549
  • CF fender trim set – $349
  • CF rear fender splitters – $599
  • CF rear diffuser – $549
  • CSL-style front grille – $550
  • CSL yellow DRL lights – $300
  • M Performance shark fin – $237
  • BMW floating center wheel caps – $129

Exterior total: $6,133


M3 interior
  • M Performance seat backs – $1,530
  • M Performance steering wheel – $1050
  • M Performance door pins – $108
  • Seat belt shoulder pads – $90
  • M Performance floor mats – $270
  • Alcantara airbag cover – $209
  • IND M Performance shifter and boot – $809
  • Ceramic window tint film – $350
  • 3D MAXpider cargo mat – $112

Interior total: $4,528

Engine Bay

The engine bay on my M3.
  • IND painted engine cover – $579
  • Fall Line Motorsport strut brace – $1,695
  • CF radiator cover – $340
  • Blackline caps – $228
  • Downstar dress-up bolt kit – $399

Engine bay total: $3,241


M Performance Suspension
The M Performance Suspension.
  • AWE Track exhaust – $1,895
  • AWE mid-pipe – $285
  • Armaspeed CF intakes – $1,580
  • M Performance suspension – $1,790
  • Future Classic wheel spacers – $398

Performance total: $3,983

Math class wasn’t required in art school, but I know enough to add everything up to $14,885.

Yes, that’s right, as much as a Mitsubishi Mirage.

I’m not saying I’m done with the car, but this represents a typical M3 build.

The fancy car mod tax, and the cost to be cool

E92 M3
You can easily double the price of a car with modifying it, but you also double the fun quota.

Kerry, don’t look at this list and be intimidated. As you go up the car ladder over the years, you may find yourself in a BMW, Jaguar or Mercedes. Or, you could go even higher and sit inside a Ferrari, Porsche or Lambo. Each financial level comes with its corresponding modification cost.

Is the intake for an M3 different from an FR-S? Somewhat – an M3 has two. But let’s compare apples to apples as much as possible. A Mishimoto intake for an FR-S costs $366, while one for a G80 M3 (non carbon fiber) costs $832. That’s about $100 more than double the FR-S. That’s a small example of the fancy car mod tax – the more the car costs, the higher the price gap.

F80 M3
A supercharger, or here, a custom interior, can make all the difference.

I would not put a part on from a brand I haven’t heard of before. Things can go boom, and altering your car already takes it out of warranty. Without a company to stand behind their product, you’re left to foot the bill.

That also doesn’t mean you need to go for something like the M Performance line, or TRD in Toyota’s case. Doing so would have doubled the cost of my M3 build, for no gain in quality.

Do your research, and save up for something better when warranted.

Why modified cars aren’t worth much more than stock ones

Would you like a complete 86, or a stock one for a blank canvas?

Kerry’s also noticed that when it’s time to sell your modified car, it’s not worth nearly what all the upgrades actually cost.

Part of it is because, hey, the parts are used. It’s also a matter of finding the right buyer – they have to actually like the changes you’ve made.

But auctions have made it easier, and it depends on the kind of mods done. Here are two 2012 M3 Coupes, optioned almost identically:

The more expensive car has a lot more modifications, but is also accident-free, with bearings done. It’s a large price gap for two cars that are very close in spec.

The point here is not to mod with the intent of increasing value, but to your own personal tastes. If done right, you can enjoy a slight increase over a completely stock car.

Just don’t trade it into a dealer.

Tips on modifying your cars

E46 M3
Some say “Ew” because of the JDM wheels. I say, you should do what you like.

It would be a cop out to stay I love every mod, or every build. I do not. My advice?

  • I’ve never seen a wrap I like. Aside from Xpel Stealth, everything looks bad once you get up close. Wraps are what they are – a cheap way to change your look. But if you’re asking me to pick between the Daytona Blue M8 that’s real, vs the wrapped one, well…
  • Take your time picking an exhaust. Listen to as many as you can, in person. Don’t rely on YouTube clips. And don’t pick one because everyone else has. I’ve only met two G80 owners with the AWE system, and one with a Borla on an E9X.
  • Make sure you love the car before you touch it. I can spend all day on Cars & Bids, pointing out cars that people bought only to try and flip 6 months later with some changes. Please – this is a terrific way to lose money.
  • I like a balanced approach – performance, looks, and the interior. Many skip the inside because you can’t see it. But I see it all the time, and I think it’s key to making a car feel unique.
  • Lastly, as a dad – be smart with your money. I know people that have purchased $10,000 wheels and will need years to pay them off because Amex has a 25% interest rate. If you can’t afford it right away, wait, and don’t settle for a cheaper part just because it means you’ll have made the change faster.
E34 M5
Talk abut tasteful. And better.

In the end, I’m really proud of my “build”. I hope you are proud of yours too. Seeing it all done up makes it worth it.

Now, how can I sell my kidney – I need to get a carbon fiber hood…

Want your car reviewed?

If you live in the tri-state area and want me to check it out, send me an email! 

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I use Nikon camera bodies and lenses, a Westcott Ice Light 2, Manfrotto tripod, B + W filters and an iMac Pro to make the art you see here.

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