I just unlocked some hidden features on my wife's car using this 'free' device

You'd be forgiven for not knowing this, but the car parked on your driveway right now might be missing out on features that have been "hidden" or deliberately made inactive.

For example, it might be able to fold away its mirrors automatically, or it might have a digital speedometer.

There might be a way to disable stop/start, or even change the way some of the lights work. You can even change warning sounds and other audible alerts.

This sort of deactivation is usually found in German cars and BMWs in particular, have plenty of them. And my wife drives a BMW.

This device, which you can pick up online, can allow you to dive deep into the car's central computer and safely control some of these hidden settings, using an app.

One of the first things I changed on our 2016 BMW M235i was adding a digital speedometer. I can't understand why it wasn't enabled in the first place, and it's such a nice addition to the driver's display.

I also configured the stop/start to remember the last setting it was left on. My wife prefers it to be off, and I don't mind it on. Given she drives the car more often, she can now start off with it disabled.

I also found a way to make the car default to its economy setting. I didn't tell the wife about this. She usually likes to jump straight into the car's sports mode, but she never asks the bill payer's permission, so to speak. So that'll save me a few quid.

We've added a different start-up logo to the main screen, told the car to beep when it's locked, and made the passenger mirror tilt when we engage reverse. It was all very easy to do, and took around half an hour all told.

There are other functions I could have played with. I could have disabled the seatbelt warning, but we always wear seatbelts, and rightly so, and I could have enabled "video in motion", but I'm nervous that Her Ladyship might drive home watching the rugby one day, get into a crash, and then I'll have loads of paperwork to sort out.

Not all cars can be coded like this, but BMWs are particularly malleable. All you need is the right tools.

The tool I used is a Carly OBD scanner, and the scanner itself is free, you just need to sign up to a plan. Handily, there's a 20% sale on at the moment, so the full access for a BMW, for instance, is just £35.99.

That not only gives you a load of coding fun and games, but it'll diagnose any faults that arise, let you clear "check engine" lights and, importantly, tell you what might have caused the issue and how much it might cost to fix.

You might even find you can fix a fault yourself, and the app's Smart Mechanic system will walk you through the process.

So even if you can't code your car with a Carly - click here to see if you can - it's worth every penny, because it could save you a fortune on your garage bills.

Click here to claim a free scanner, and 20% off the full package.