Mini Paceman diesel issues

Sounds familiar! I had similar symptoms with my old Vauxhall Astra – higher fuel consumption and difficulty starting. Have you tried throttle cleaning? A dirty throttle valve can cause all sorts of problems. The engine throttle controls how much air goes into the engine, and if it's gunked up, it won't work properly. If the "throttle position" sensor isn't reading correctly, it messes everything up. It's worth a shot before you start replacing parts. A can of cleaner is cheap.

Throttle cleaning, eh? I'm not entirely sure I follow. What exactly does the throttle valve do, and how would cleaning it affect fuel efficiency and starting?

Okay, so the throttle valve regulates the airflow into the engine. Think of it like a tap controlling the amount of 'air' going in. When it gets dirty, it sticks, which throws off the air-fuel mixture. That’s why your fuel efficiency goes down and starting becomes difficult. But if the accelerator pedal module is defective (the thing that tells the throttle valve how much to open), cleaning won't fix it. It's likely faulty and needs replacing. I'd suggest getting it checked out by a workshop; they can diagnose it properly.

Took the Paceman to the workshop as you suggested. Turns out the accelerator pedal module was indeed defective, causing the throttle valve to malfunction. New module and labor cost me 205€. Fuel efficiency seems back to normal now. Thanks for the advice!