Every car I’ve owned has eventually faced the same question: what else were you built to do? Not modified in the fast-and-loud sense (I’ve never cut a spring or glued on a wing). I mean the quieter obsession: the factory designed this platform to support features my particular car didn’t ship with, the wiring or the software or the mounting points are often still there, and somewhere in a service document is the proof. The build sheet records a purchase decision somebody made at a dealership years ago. It doesn’t have to be the last word on what the car can do.

This is the origin-story post for the Garage section, because the current project (a factory tow hitch Tesla insists doesn’t exist — that story is coming in its own post), makes more sense once you know it’s the third generation of the same instinct.

2010: the F250 navigation unit

It started with a 2010 Ford Escape XLT and a navigation head unit pulled from a 2009 F250. Same corporate parts bin, very different window stickers. The physical part of the swap only takes a Saturday. The electrical part was the real project, because the truck radio and the little SUV had never been introduced to each other.

The key was Ford’s AS-BUILT data (the per-vehicle configuration record that tells every module what the car is and what it’s allowed to do). Load the AS-BUILT values from a donor vehicle whose build did include the feature, and the electronics stop arguing. I fed my Escape a section of a 2010 Escape Limited’s configuration, and the nav unit woke up believing it had always lived there. Drop it in reverse and the camera screen came up, ready and waiting — for a camera I hadn’t actually wired in yet. The pigtails and the custom wiring came later, but as far as the modules were concerned, that camera had been ticked at the factory.

That swap taught me the foundational lesson of all of this: modern vehicle features are parts + wiring + configuration, and the configuration is just data. Data can be read, understood, and (done carefully, with the service documentation open) rewritten.

2013: the tow package that Lincoln forgot

Next platform, same move, more copper. The 2010 Lincoln MKT EcoBoost (my beloved black-on-black sleeper) shares its bones with the Ford Flex, and the platform supported a factory tow package mine didn’t ship with. So it gained one: the real thing, factory parts, factory routing, documented on the owner forums as I went. Along the way that car turned into a rolling seminar on the rest of the discipline: talking other owners through retraining the collision-warning sensor after bodywork, EcoBoost charge-air plumbing, and the eternal truth that the parts catalog knows more than the sales brochure ever admitted.

The MKT era added the second lesson: the factory’s own engineering is usually the best aftermarket kit you can buy. It fits, it lasts, and the documentation (diagrams, torque specs, connector part numbers) already exists. You just have to be willing to read like it’s your job.

2022: feature flags on wheels

Then came a 2021 Model S. Does a Tesla even have an AS-BUILT record? The short answer is no, not in the Ford sense. What it has is a gateway config: a file of feature flags living in the gateway controller inside the MCU, telling the car’s software what hardware it believes it has. Change the config (through Tesla’s own Toolbox, these days with a paid day pass), redeploy, and capabilities appear exactly the way my Escape’s camera screen did sixteen years ago.

The architecture is genuinely elegant (zonal controllers, smart devices on LIN and CAN buses, one config to rule them), and it’s made possible things the Ford era couldn’t dream of: matrix headlights on a car sold with the lesser lights, a passenger-lumbar retrofit done over a weekend on my wife’s Model Y, tail lamps from a later revision, the tow-hitch project. The instinct is unchanged. The difference is the posture of the manufacturer: Ford published AS-BUILT structure openly enough that a guy with a laptop could learn it in 2010. Tesla treats the equivalent layer as theirs, on a car I own (an approach I once described on a forum as very Apple, and I didn’t mean it entirely as a compliment). The capability being in there, behind a flag I’m not supposed to flip, changes the project: the engineering is still the engineering, but now there’s a negotiation with the manufacturer sitting on top of it.

What sixteen years of this actually teaches

Read the service documentation first, opinions second. Every one of these projects began in a wiring diagram or a parts catalog, not a YouTube thumbnail. The documents don’t care what the counter says is possible.

The gap between trims is where the fun lives. Manufacturers build one platform and sell it as five cars. The wiring for the car you didn’t buy is frequently sleeping in the car you did.

Configuration is the modern crowbar. In 2010 it was AS-BUILT hex values. In 2026 it’s gateway feature flags. In both cases, the difference between “your car can’t do that” and a working feature was never metal — it was a few bytes of permission.

And know when you’re done. Not every gap is worth closing; some retrofits turn out to be a lot bigger than they look on paper, and the fog-light adapter that once cost me a tow truck (a story for another post) taught me the price of forgetting that. The discipline isn’t doing everything; it’s knowing what the platform supports, and choosing.

The Garage section will mostly be these stories: current Tesla projects, the occasional MKT flashback, and the tooling that makes it all go. If your car’s build sheet has ever felt like a suggestion, you’re among friends here.

Thanks for reading!