What separate it from the sedan ? firstly, most apparent is the 3-door body with 180 mm boot chopped and replaced that by a liftback. Additional strengthening required for the tail’s big opening makes it just 10 to 15kg lighter than the saloon. With rear seats down, it provides a 1100-litre luggage space, exactly the same as the 3 Compact. Despite of 20 mm lower roofline and a fastback tailgate, rear seats are still roomy enough to swallow a couple of 6-footers. Optional electric glass roof eats into headroom but it makes the cabin feels light and airy. 

The second change is stiffer springs and dampers. The standard setup is roughly between the saloon’s standard setup and sports setup, while the sports setup is another 10% stiffer. This results in a ride slightly firmer than the saloon while providing marginally better control and agility. Considering the high achievement of the saloon, you might think the Sports Coupe must beat the new Compact in handling ? wrong, because the new Compact has been tuned even sportier, overshadowing the Mercedes in every dynamic aspects (including steering feel) while matching its ride. The Sports Coupe is taut and grippy, steers accurately and feels agile, but being a coupe it faces some rivals offering greater feedback and quicker response. It works best at 80% rather than at limit. 

Market positioning could be tricky, because Mercedes has already got a CLK coupe (based on last generation C-class) above it. It marginally undercuts the saloon with equivalent engines, so budget-limited buyers are left to 316ti Compact. C180 Sports Coupe is slow and expensive, so unless you want its badge and design it is not a very sensible buy. Unluckily, other versions are not much better - 163hp C200K and 197hp C230K are powered by supercharged fours which are notorious about NVH. No match with BMW’s 2.5-litre six at all. Although the 230K provides quite good performance (even in automatic), the engine sounds coarse and feels reluctant above medium rev, preventing the driver from enthusiastic flat out.  

While the saloon and CLK have 3.2 V6 to choose from, Mercedes decided to limit the Sports Coupe to four-pots only to avoid internal competition. This is of course a big mistake, because the V6 would have made the Sports Coupe a really desirable car. It beats the Compact easily in beauty contest. It offers more room. It doesn’t handle as well but still good enough. What it desperately need is a decent engine. Listen, Stuttgart, give it a V6 as soon as possible ! 
 

M271 four-cylinder engines

At the moment of writing, M271 family consists of 4 engines. Surprisingly, all of them displace 1.8 litres.  
Different combinations of output and fuel consumption are implemented by different tuning, e.g., different supercharging pressure and compression ratio. The only exception is the CGI engine (CGI - Stratified Charge Gasoline Injection), which employs direct fuel injection. As usual, direct injection not only saves fuel, but also increases power by allowing higher compression ratio. The 4 engines are:  
   

Compare with the old 4-cylinder, the M271 family is much smoother, quieter and much more frugal. Mercedes finally has a world-class four-cylinder engine to match its superb V6, V8 and V12. 
 

C-class Sports Coupe with new engines

The 4-cylinder series included C180 Kompressor (143hp / 162 lbft), C200 Kompressor (163hp / 177 lbft), C200 CGI (170hp / 184 lbft) and C230 Kompressor (192hp / 192 lbft). The entry-level unit is considerably more torquey than the old C180 Sports Coupe, thanks to supercharger, thus real-world performance suffers little from the old car's sluggish response. In fact, its performance is easily more accessible at low and mid-rev than BMW 318ti Compact, while good refinement should put smile on your face.  

At the upper end, the C230 Kompressor loses a bit power and torque from its predecessor, as engine displacement has been reduced from 2.3 to 1.8 litres. Inevitably, performance eased back a little (0-60mph is now 8.1 sec), but the smooth and quieter power delivery is more than enough to compensate. In the past, the more you ask from the engine, the more unhappy it becomes. In contrast, the new engine adds to driving fun.