Please see my comments for a 1991 230CE. I think this is the model you're looking at. Feel free to email me at email@example.com for any questions.
Recently purchased an E320 coupe, with 156k (FSH). What can I say??... fantastic in every way... fast, classy and solid. Just don't thrash them too much, they are old cars don't forget!... (I thrashed an E280 a few years ago and blew the gearbox)
I own a E220 coupe and an E300 24v saloon, both these cars run beautifully. The 6 cylinder model is smoother, but at speed not much difference between them, and the four cylinder has far better fuel consumption. Either way, buy one, you won't regret it.
I've had 4 of these cars over the years. I had a basic E200 with no extras, did 169,000 miles, it still drove like new. Everyone who ever traveled in it commented on the smoothness. I always claimed they all drive like this (and they mostly do). Great cars .
I own a e220 coupe 1995 late model, it runs smoothly with good consumption rates even when cruising at 140 km/h. It also offers that pillar-less beautiful ride!
My advice when buying such models is to look for full service history, it will save you some money in the near future and also offer you a more reliable future.
FSH is important since these cars were expensive to maintain, so a FSH shows that previous owners had the car in top condition. Also it's a big plus when one day you sell your car to have a booklet with FSH due to their age and costs, it makes buyer make an easier choice over your car!
Also besides FSH, check the car's worn areas like interior seats, steering wheel, plastics, outside panels for rust etc. The more original the car looks, the better it would be because it means previous owners loved the car! The more aftermarket non original parts, the more it indicates that the car was probably abused. Most of the times that is the case. See you around.
Got a 94 E220. Can't believe that nobody has mentioned the rust problem. Not only my own, but ALL the W124s that I've looked at over the years have serious rust problem with the rear inner wheel arches. They rust at the bottom where the plastic sills collect mud and stuff. There are a total of five inspection holes lining the inner wheel arch, and when the rubbers bungs deteriorate, rust sets in. Bad news, and I guarantee that these cars will never last forever.