Originally Posted by loudandheard

C32, slk32, and srt-6 can be had for very reasonable prices. I would recommend 2003+ for C32 because of a potential issue with the cams, never proven, and radiators leaking into the transmission. The radiator issue would probably have been taken care of by warranty or the previous owners. You can check by the looking at the brand of the radiator. If it's a valeo replace if behr you are good to go.

The intercooler pump tends to go bad and will make the car feel bogged down. The ecu will pull timing because of the heat, so the car will not feel so fast. The heated seats go bad on all the mercedes and they are integrated into the seat cover, warranty will usually take care of this issue. The seat control modules tend to go bad, but there's a fix or you can buy an updated part. Door locks can go bad, but the lock is around $100 and can be a pain to replace, but can be done. Sound system is easy to upgrade either with factory parts or aftermarket parts.

The engines are fairly solid, but there have been a few members that have had issues, but most of them were from 2002 and modded. I think it has to do with the cam lobe shifting over time, but it's never really been proven. With all mercedes you get the usual oil leaks. Most of leaks I have encountered are from valve covers, the front main seal, rear main seal, oil cooler, and power steering pump. Most of the seals are easy to replace except for the rear main seal. Maintenance on the car should be a piece of cake for you. Oil change is a piece of cake if you use an oil extractor and the oil filter is top mounted, filters can be found for $10-$15 and the oil is mobil 1 0w40. Trans flush is fairly simple, but you will just need the right tools and you can find the fluid fairly cheap now from ryder. The differential fluid change is very easy, just need the right tool. The coolant flush is simple and the intercooler pump change is simple as well. The coolant that I use is valvoline Zerex G-05, essentially the same fluid mercedes uses just half the price. I've made DIY for just about every thing I've listed and I have a list of fluids that replace the factory fluids and are usually much cheaper. Supercharger pulley tends to wine because of the bearing, but it's a cheap and easy fix. I've heard of the water pump pulley shearing off, but you can get a pulley saver kit which can help reduce over rotation from adding a larger crank pulley.

Brakes are easy to change, but you will spend a bit over $600 if you replace all 4 disc, pads, fluid, and upgrade to stainless steel brake lines, if you do the work yourself. The job is simple and there are various DIY's.

As for engine modifications, there are tons of options and a few are still available. There are various crank pulleys to increase boost, 178mm, 181mm, and 185mm are the sizes and it's recommended to get a tune to adjust airflow and it really increase performance. There's a new smaller supercharger pulley as well which increases boost and can be a bit easier to replace than the crank pulley, but that's fairly simpler too. Cooling mods are recommend if you do a pulley, usually just an upgraded heat exchange. Headers are an option if you can still find them. You have the option of shorties, equal length, and long tube, but most of the ones you can still find are short tubes. Mainly the major tuners still sell them, such as kleeman, renntech, and evosport. You can do a dual exhaust, but it can be a bit difficult to get the right sound, most people complain about droning. A lot of people just eliminate secondary cats and the resonator and call it a day, but everyone wants the c55 dual exhaust look. Intakes help a lot too, most people go with an sl55 intake which can be had for around $500. You can get the speed shift tcu tune from eurocharged, which also provides most of the tunes everyone uses and the crank pulleys. There area few options for custom intakes, but we don't have a lot of space in the engine compartment like the slk32 and the srt-6. With an intake, larger heat exchange, 185mm crank pulley, and a tune, you can be in the high to mid 12's if not better.

As for cosmetic mods, there are body kits that you can some times still find, brabus, carlsson, and a few other I can't think of. You can get a carbon fiber front lip for around $250, you can get a rear trunk carbon fiber spoiler for $100, and a rear diffuser for around $250. There are various options for wheels, but most prefer to stay with 18"s which do not come stock with the c32, you get 17"s. When you purchase the C32 try to get the car with bixenons because they can be costly to purchase after you purchase the car and it makes the car look that much newer.

Take in mind most of this info applies to the C55, except for some of the mods and some of the issues specific to the C32.

You could consider getting a kleemann c55k, which can be had for fairly reasonable prices if you can find them.