BMAX Poor Starting and High Fuel Consumption

It's possible. Have you checked the throttle position sensor? A defective accelerator pedal module can cause those symptoms in BMAX models. Is the engine idle stable, or is it erratic?

I haven't checked the throttle position sensor specifically. Where is the accelerator pedal module located, and is it easy to inspect myself, or is special equipment needed?

The module is near the pedal itself. Visual inspection is possible, but testing requires diagnostic equipment. Given your symptoms, a defective throttle valve, or its associated components, is likely. I suggest a workshop visit for proper diagnosis to avoid further damage.

Thank you for the advice. I took it to a workshop, and they confirmed a defective accelerator pedal module. The repair, including parts and labor, cost 205€. The car is now running smoothly again.