Apparently a relatively common issue on the turbo-engined versions of this generation of Smart, a faulty camshaft solenoid valve often manifests itself through rough idling… or in my case wildly fluctuating revs on cold starts.

The always excellent Evilution website has an explanation and fix for those suffering from this problem, so I won’t go through a step-by-step here, but I just wanted to show a more extreme example of how these cars can react to a bad solenoid valve than the more usual bad or rough idling symptoms.

The old solenoid valve wasn’t in a visibly terrible state, nor did it come out of the engine in multiple parts as in Evilution’s example; nonetheless swapping it out for a new one – I chose the Renault equivalent as it was the easiest (and cheapest!) to find online – solved the problem immediately.