There are plenty of reasons why a diesel won’t start in the morning. This can often be traced back to a problem with the fuel system or the glow-plugs which are needed to warm the combustion chambers before the diesel will ignite.

As for the noise, it pays to remember that diesel engines are inherently noisy, but if you’ve owned the car for a while and are familiar with its normal level of racket, then any new or louder noises signal a problem. If, indeed, the new noises are connected to the engine’s refusal to start easily, you might be looking at an engine with worn out internals. At that point, it’s time to recondition or replace the original engine.

But before you do any of that, have a diesel specialist look at and listen to your engine running, and you might find the problem is a simple one after all.

Like a lot of relatively modern vehicles, the X200 doesn't use a throttle cable, but is instead what's known as throttle-by-wire. That means that the accelerator pedal tells the car's computer what position the driver has placed it in, then the computer tells the throttle to respond accordingly.

It all works on electronics and position sensors and if anything goes wrong with that arrangement, you can get erroneous messages being sent to the throttle with the symptoms you've mentioned. An electronic scan of the vehicle should reveal what's wrong as the computer will have recorded fault codes with any of this electronic gear.

Beyond that, it could also be something rather more mechanical such as a sticky stepper motor (that physically opens the throttle) or even a vacuum leak. It could even be a fault with the electronic protocols that tell the engine to increase its idle speed when, for instance, the air-conditioning it turned on. Again, though, a scan at a workshop should reveal all.

It’s appears not to be selecting first gear. It could be a number of things in the transmission. It may be that it just needs servicing. Take it to an automatic transmission specialist.