It seems I have the original analogue based radio unit in the car, looking to update it to something suitable for today's technology and uses e.g. bluetooth, DAB, etc. Any recommendations? Also is there anything I need to do different from a fitting perspective?
I just replaced the original factory head unit in my very recently acquired '99 SLK230K last evening. I walked out to the car at 11:30PM with the new head unit, and with nothing more than the dome light, had the old radio out and the new one in, working, and configured in 10 minutes.
How was this so simple? Crutchfield. https://www.crutchfield.com
I bought a cheap-o refurb'd JVC head unit for $70, because honestly I couldn't stand the factory radio for another day BUT haven't decided how far I really want to go with the car audio in the long run. So I may be done, or this might just be a placeholder.
But the joy of Crutchfield is, cheapest head unit they had notwithstanding, I STILL got the radio removal tools, antenna adapter (US to European) and that greatest of things, the wiring harness.....all included at no extra cost.
(Skip this if you already know this, but the beauty of getting a wiring harness is that it's made to attach directly to the car's wiring harness that you'll unplug from the factory radio. So you just look at the wires coming off the new head unit, and match them up one by one (99% of the time by matching color-to-color) to the wires on the new harness, and crimp together. Remove old radio, unplug the car-side harness from it, plug that to the new harness that's already crimped to the new head unit's wires, and you're done. If you do NOT do it this way, you end up cutting off the car-side factory harness and now have to match up the wires to those on the new head unit. They may-or-may-not be the same color on the car side as the 'standard' colors used in the aftermarket, so that means you'll be using a multimeter to get all the power wiring hooked up right AND your ears to get the speakers hooked up right...plus you'll have left an awful mess for whoever may follow in your footsteps someday - who might be YOU if you replace it again someday - and that person will curse you forever as then undo your mess....
So here's how the install took only 10 minutes, in the dark, by the light of the dome light and nothing else:
1. I did spend 15 minutes sitting on my couch, watching TV and crimping the new head unit's wiring to the new wiring harness. But that doesn't count since I was enjoying 2006's The IT Crowd from your side of the pond while doing so...
2. I spent 1 minute using the free removal tools to slide the old radio out.
3. I spent 1 minute unplugging the harness from the old radio, and also a very fancy-schmancy plug (optical?) for the factory phone system, I think, that I don't have AND some other plug with 3 wires that I have no idea what it was, but don't care because I've got the Crutchfield supplied wire harness that does my thinking for me.
4. Another 2 minutes fitting the "sleeve" (metal rectangle the new radio slides into) into the hole in the dash, and securing it by bending the little tabs that hold it.
5. Another minute to plug the new harness to the factory car-side harness and slide the radio into the sleeve. (Remember, the new harness is already matched up wire-for-wire to the wires on the new head unit.)
6. 5 seconds to pop the black plastic trim around the radio to cover the seams and make all pretty. (I did not include this in my original estimate, so, call it 10 minutes and 5 seconds if you insist...
7. 5 minutes configuring the new radio (including the most important part, color-matching it's display to the exact right shade of orange to match the factory dash lights. If not for my insistence on being able to do this, I could have bought a $10 less head unit that had only red, green, or yellow color options...
) and clean up.
Seriously, that's it. I did not even bother unhooking the battery, which yes is recommended but having done this before I knew there was ZERO chance of shorting anything (since it's just unplugging/replugging a wire harness) and with the key off only 1 wire, the 'constant power' battery backup wire, has it's 12v on it and of course you've got a fuse there if you REALLY do something stupid...)
So, you CAN get your radio elsewhere cheaper, BUT if you don't get the radio removal tools you absolutely need to get those. You can live without the wiring harness if you're willing to cut the factory harness end off the car and then just splice up your wires from the radio to the car - but that'll take a bit longer AND make anyone who ever follows your footsteps (including you, if you get another head unit in the future) curse your name for all eternity. If you buy a stereo that already has the European type antenna nipple you scan skip that adapter also. (If your choice of head unit doesn't have pre-amp outputs you need yet another adapter to drop the speaker-level outputs back down to pre-amp levels....BUT....unless you are buying a vintage collectable 1991 era head unit, you'll have them...
As for what brand of stereo to buy, or features, that is pretty subjective to you and given that this cheap-o JVC had all the good stuff such as the USB port on the front (the only thing I cared about) which is also a 1.5 amp charging socket - you can pop in a thumb drive and play music (up to and including FLAC support) OR connect your Apple/Android to charge and control the radio via app, including Pandora, iHeartRadio, etc. and Bluetooth for anything (music, phone integration, etc.) and so on......then any more expensive option has to have all that and more, I'm sure.
But when it comes time to buy, I can't recommend Crutchfield enough. Unless you save enough on the cost of the head unit buying it elsewhere to still save money after paying for the harness, tools and adapters it's just not worth doing it any other way. IM(NS)HO of course.