While weighing a few cars the BS popped up in my head and now I just can't seem to put it aside... My options for a car are a 997.2 GT3, GT350R, and now the CLK63 BS. Whatever car I end up getting would be my only car and subsequently the daily driver. It will see a few miles (15k/yr min) as well as spirited driving almost every day. That being said, would the BS be a realistic daily? How are these cars holding up now that they're 13yo? Anything to look out for in a BS?

Appreciate any input, thanks!

The 997.2 RT3 and the GT350R are both track oriented cars and not really suited for daily use. The GT350 not R would be a better choice. The Black Series has been used by many on this forum as a daily. In my opinion there are many cars better suited to a only car and daily driver.

Do a search for Daily Driver. There are a few treads on it. Hope this helps.

I've daily driven an e46 m3 for the last 14 years and honestly think the CLK is a bit better at daily duties due to the torque on tap and auto trans. My suspension is in full hard mode and max camber so it is significantly stiffer than the m3, but it doesn't jar you around as much due to the massive bolstered seats.

Out of the choices you listed I would think the CLK is best suited for those duties. That being said I agree with Gene that there's better options out there for putting 15k miles on in a year.

Here's a more recent video that talks about some of the daily characteristics.

In the words of the Starsky & Hutch remake...Do it! Enjoy the car for a year. If you don't like it sell it. I'll bet you a steak dinner you'll love it. One of my deciding factors were the forum posts where people sold their CLK63BS and eventually bought another one back (with no intention of selling again).

Con 1 - for daily it does not have BT. Easy fix, get a BT adapter to plug into the ipod dock if the car is so equipped. Its in the glove box. No calls, but you get your streaming music. Dealer has options too.
Con 2- it is not discreet. It is not a F-car or a 911, but it has a ton of presence. People don't know what it is, but they know it is something. Limo black tint looks great without the B pillar (i'm partial) and accentuates the lines of the car imo.
Con 3- they only made about 500 of em. Would love more so you don't feel bad packing on the miles. That said, you only live once, you can't take it with you. If you find joy in the driving experience, this car should be at or near your top.
Con 4- M156 has a few known issues across the entire MB range. Repairs, warning signs, and fixes are becoming well documented if you want to wrench yourself or take to an indy/dealer.
Con 5- Have not worried about parts, but i am wondering what the inventory will be like as these age (from use or just sitting). It is a Merc, the build quality is high and the package is aging very well. Good news is the non CLKBS specific parts (window switches, A/C, etc) are a dime a dozen given all the CLK's made.

Pro 1- you don't need BT, you have 500+hp of exhaust note. It's intoxicating for both driver and passenger.
Pro 2- the other options mentioned are great cars. The 350r will probably be closest to the CLKBS in tail wagging drive but I would not know. It is a matter of opinion but there is a certain je ne sais quoi about the whole CLK63BS package. Classy yet ready to throw down at any time. The GT3 will be surgical, all the time. The 350r to me is pure Americana (yes I'd love to own one for a season but not forever). Seat time in a bunch of Porsche GT(x) and they are all great, but not smile evoking like the BS. Drive a Black Series and you'll understand. There is a YT video of a guy who sold his GT3 for a CLK63BS and does not regret it one bit.
Pro 3- They made about 500 of em. Each year a few more are likely taken out of population. I am sure all Black Series owners are partial - the car really is beautiful. The roof line, fenders, and headlights border on art how it all comes together.
Pro 4- M156 ENGINE!!! Was talking with a guy who had a C63 with the M156 and now has a GTR. Loves the Merc GTR, but misses the M156 engine. That should say something.
Pro 5- I'd love to pick up a high mileage, original, well maintained CLK63BS after you are done with it for a pet project I'm starting to formulate. Do set aside funds for oil changes every 5k and gas. You should be able to extract value upon sale being able to document the oil.

It all comes down to what you want out of the car and the mood the car puts you in. You have three good choices, albeit with different personalities. Agree about the track focus for the other two mentioned. For me, the CLK has and continues to deliver the experience I am looking for which is joy in an often joyless world. I won't comment on the ride. This is completely subjective but given your three options i think you already know what you are signing up for. I find the CLK to be firm, yet not punishing. I verified the suspension is at the stock settings. Happy shopping and chime in with a pic if join the community.

To specifically answer your question, other than the usual (accident damage/etc) the only thing I’d like to see for you is consistent and early oil changes or oil changes done annually if low mileage use (less than 4-5k per year). If bought right, at worse you’ll be parking money. Not sure the same is true at least for the 350r.