ok, not an SLK

but a 2001 S210. I went from the audio 10 to the audio 30 ( Becker) single din sat nav, ( no flip up screen). It was fine, integrated with the car's interior perfectly, and all the steering wheel controls worked as well. I did have to find the wire with the speed signal data in the passenger sill, tap into it, and run that to the block connector and connect it in there. I also had to route and mount the satellite antenna. Not that difficult all told, but fiddly.
I then upgraded that to a Becker Indianapolis, which despite similar looks and the same kind of integration, is a far superior unit, and it has a 3.5mm aux input capability. It does not have fibre -optic, so I lost the steering wheel button functions.
There would be no trouble getting either of these into an SLK, but you would probably have to find the speed signal and route the nav antenna. I'm pretty sure the audio 10 I had in mine had no GAL speed related volume function, which means there is no speed signal coming to it. Neither does the SLK have steering wheel control.

 

I bought a car that had an upgraded JVC unit with USB/MP3/CD/AM/FM Radio and I was happy with the sound as he had fitted it with custom speakers in the trunk and inside cabin. The radio signal was weak so I had a antenna booster installed.

I however wanted GPS/BLUETOOTH and a BACK-UP camera also. I got the advice of a place specializing in car stereos and electronics. I was warned off the signle din systems with the flip up screen as over time they tend to break. Also when the screen was up it would interfere with my access to some dash controls.

I instead went with changing my rear view mirror with one from Audiotex with all the features I needed. If you are in an area that allows for radar detection it also has a feature to enable it. Unfortunately I am not in such an area.

The only draw backs are that when you do have the GPS/BLUETHOOTH SCREEN ON it takes getting use to and to continue using it as a rear view mirror. (MAPS and the MENU TAKE UP HALF OF THE REAR VIEW MIRROR WHEN THE SYSTEM IS ON. I DRIVE WITH THE REAR VIEW MIRROR FACING ME TO AVOID ANY GLARE).

A simple solution was to buy another portable small rear view mirror that I suction cup to my windshield. Its very small but it does the job for me. Parents use a similar mirror when keeping an eye on their kids in a car with backseats. I can use it, or not, as it comes on and off easily. I made sure to buy one with the best suction cup I could to make sure it will not fly off in a collision.

I had the entire thing installed by professionals as I didn't want to screw anything up with the existing system. So far so good.

 

or.... you can use your smartphone for navigation and just upgrade your headset.

 

I did think about that but I guess I'm just old school... I do have a smart phone but not sure how it works together with radio. Will navigation from the phone mute the radio? Can you listen to the radio while navigation in progress? What if I get a phone call? I would still have to change the headset to get the display so why not get nav built in? I do appreciate your input.

 

in case you are a bit modern

what I did with my SLK ( although why, I don't know, as I can't think of a car I would enjoy being 'lost' in more) was I bought a Garmin Nuvi 55. It is just the right size to sit propped up in the open dashboard tray above the vents. I put some Velcro down in that, and some Velcro on the sucker side of the Garmin mount. I also hid the power cable from the cigar lighter, up the side of the dash panels and have plenty in there to plug into the unit. It looks pretty good, is just where you need it in the eyeline and does not obscure your view of the road. It can be angled to you, or your passenger sorry, navigator, and is easily unplugged, or can run on battery power.
You could of course use any other similarly sized, or even bigger sat nav unit. I'd be hesitant putting a tablet on there, just for the accident risk it poses.
I then replaced the audio 10 with a deckles radio/mp3 unit with Bluetooth. I only take incoming calls, and only from the most urgent of sources ( wife and kids). If you need inspiration, lmk, and I'll take some pix, now that I have imageshack capability>

 

I used that Garmin Nuvi and it does fit nicely in the cup holder and you can position it great for viewing. I didn't run the wire inside the dash though; I just used it plugged into the cig. lighter. Worked great! Had I not wanted a back-up camera and not wanted to add a dashbaord adapter for my bluetooth, I would have done just what Elmer did.

 

Not a fan of putting anything in the cup holder/tray. I find that any weight over time will eventually crack the plastic (already see stress marks) plus removing the unit to close the tray would put stress. Also notice that the tray shakes while driving (unless a smooth new road), would that not give you a headache after awhile? I usually lay my smartphone (with an anti-slip rubber case) right over the center small compartment (where the cig lighter is on the R170). It stays there pretty well. I did upgrade my headunit to a kenwood with bluetooth. Using my smartphone, I get free updated google maps for navigation and live traffic updates.

 

+1 on the rattles. The thing doesn't weigh that much though, and probably a lot less than two cups of Costabucks finest java, which is what the cup-holder was engineered to take. when all is said and done, it's an occasionally annoying price I pay for the luxury of having pretty good mapping where I need it.
I actually ran it side by side with my Indianapolis ( Cd driven) in my estate car just for fun. The Indianapolis responded to route changes from me much quicker, and hauled me off the motorway for a jam around the bend I couldn't see from the road, before the Garmin even noticed. So I tend to trust the built-in Becker almost implicitly. Sadly, I'm on the last set of discs they released for it, so here's hoping the don't change the major roads of Europe too much!

 

Thanks for the input guys! I do have an older Nuvi that I've used but the map is so outdated that it hinders more than helps at times. I did place mine in the cup holder too and the line of vision was great but it kept twisting away from me. I would rather have it built in but not totally sold on it. I may look at some new Garmins too but wasn't sure if the cost would be much better than the whole unit.

 

Maybe go into a place that specializes in car audio systems. It won't cost you anything for them to look at your car and suggest what might work in terms of a system that meets your needs. At least you will know what kind of money they want and then compare it to the price of getting an updated Garmin and running
the wire so its hidden.

 

I too have an old Becker Indianapolis and that is configured for navigation, but I also fitted a Bluetooth unit to the CD changer ports and use that for music and telephone.

I have run the GPS aerial up to behind the tray/cup holder and run an aux cable and a USB charger cable to the tray so I have power above the dashboard. (I don't like running cables from the cigarette lighter socket)

If I need navigation I use Copilot on my Android phone over Bluetooth as I only have V4 of the Becker disks and listen for instructions or, if I need the map, I have a flip up stand in the tray that presents the phone so I can read it.

One tip - you can read the Becker screen in direct sunlight with the top down but that's not so easy using a smartphone!!

Taking your point about listening to the radio and following navigation instructions that works with music and navigation from the smartphone but not when listening to the radio. I'd have to check if it's different when using Becker navigation.