Under the B-Class' hood, you will find a surprisingly small (for a Mercedes) engine.
Currently, the car is only available with a 1.6-litre, turbocharged, direct injection petrol engine with VVT, which puts out 121 bhp@5000 rpm and 20 kg@1250-4000 rpm.
With start/stop technology and three driving modes (Eco, Sport and Manual), it's not exactly a barnstormer, but it has its strengths - low down performance is sprightly (the turbo really helps here), and once you're cruising at highway speeds, the motor is relaxed.
The 7-speed dual clutch transmission is also tuned mainly for refinement and smoothness, although it holds revs for appreciably longer when in Sport mode.
The performance numbers are quite respectable - 0-60 kmph comes up in 4.5 seconds, 0-100 kmph in 10.5 seconds and the 80-120 kmph overtaking manoeuvre takes 7.1 seconds.