What is is about spark plug wires that MB can't just sell the entire thing?
 

I went to replace the two spark plug wires on my newly acquired SLK230 and found that the factory replacement is the wire only and a special crimping tool is needed to fit them into the old ends which are to be re-used. Talk about flashback to the 1970s! Why can't they just offer the entire wire assembly, ends and all if that's what a customer wants to buy? Can't it be a more cost effective use of a tech's time to just replace the entire thing than to fidget around making up a wire assembly? And the crimping tool cost $150! So, now I guess I either have to make up the assembly myself or buy aftermarket wires, which is what I am leaning towards but like to use OE whenever possible...any other choices??

You can buy complete sets or individual wires,connectors , or plug ends.
So, that is the best of both worlds.
Check parts right here.

Thanks Arthur for the prompt response, but...

Apparently you can't buy the entire assembly from MB, only from aftermarket sources. Whether those are identical to OE or not I don't know...the EPC shows no PN for the wire with ends, only individual parts (wire, connectors, ends)...I was trying to keep the car OE, and avoid aftermarket but if I have to I will just order a set of aftermarket ones from Fastlane. If you know of a PN for the entire assembly from MB please let me know, but my EPC and that of my dealer's parts counter doesn't show one available.

Why do you think you need wires ..it is the plug connector/resistors that go bad.

I had a misfire on cylinder #3, which is a wired cylinder. I replaced the plugs and wanted to replace the ignition wires as part of my "tune up" since the car is now 9 years old and the parts were all original. When I went to the dealer I was shown the EPC which matches mine at home showing the wires and ends sold as pieces only, not the entire assembly...I'd hate to re-use 9 year old wire that's been baking under that cover if I can avoid it.

A wired plug misfire most likely fault is the resistor connector, not the wire. The wires are solid core.
And Beru are far better than OEM Bosch. If I just bought that car, my first ignition changeout would be new plug connector/resistors , [ specially the coil ones] and new plugs.

Arthur, thanks again for the advice, I will heed that. I assume no special tool is then needed to separate the connector/resistors from the wires and coils? If so, I will just pick up the 4 connector/resistors and re-use the wires.

The old ones get baked on, but they come off easy if you slip an ice-pick down between the boot and squirt some WD in there with that little red nozzle... [ yeah, the one you dropped and can't find now]

I just bought WD-40 in a new can that comes with a trigger top and built-in spray tube...look for it on the shelves...you'll never have to look for that little red tube again. Thanks for the information...I'll go ahead and order the ends and see how I do with it.

Yeah, I have a couple of them too ..they are just as bad..you have to flip the thing up and then after a while it does not lineup.. they should have just put a plastic press-on nozzle storage holder/clip for the old nozzle when not in use instead of a piece of Scotch Tape... User Friendly/KISS design seems to escape those that you would expect it least from...

On the waste spark motors I very seldom find the plug wire connector bad, but I'm sure it does happen. The connector under the coil are really fragile and cause lots of problems. Just for information purposes, in misfires on the cylinders with plug wire and connectors instead of coils, the misfire is actually the coil. It still works the cylinder it is on but has an internal short on the side going to the cylinder with the wire.

I went the entire factory replacement route on my 1993 400E about 10 years ago when I bought it. I thought I wanted to do it right. Mercedes sells the wire by the meter and I think the ignition wire is actually a different diameter than the plug wires. I bought the crimping tool too. If you get the tool, when you insert the caps on the ends of the wires, pay attention that the threaded stems are hollow and there is a smaller crimping device on the tool so you can crimp the threaded stem at the base after you've inserted the bare wire into it. Be careful not to bend the stem. You will also crimp the collar of the caps around the outside of the wire after that--a more intuitive application of the tool. If you didn't know any better, you might miss the fact that the threaded stems need to be crimped too. Believe me, it's easy to do. (You would probably notice it, though, when you tried to screw the caps into the boots and the wire pulls out.)

I'm not really sure the wires are like domestic cars where they lose resistance over time, but, at the time, I just presumed they were the same as my 1992 Camaro Z-28 with headers, where I always have to throw a new set of solid core, high-heat Moroso wires on every 30,000 miles. Anyone with experience here may be able to chime in. I too am interested in whether anyone has found the wires themselves to go bad. Arthur Dalton suggested in a prior post that the boots go bad before the wires do. In the past 10 years, I have only changed the resistance boots that go over the plugs.

In any case, both ends will screw off the wire with some WD-40. I would try the boots first. It may save you some money. The whole thing with wires, distributor caps rotors and the tool was well over $1,000 from the dealer and that was a decade ago.