"If, like me, you are in the habit of simply pushing the clutch pedal down at lights - something the absence of a footrest in the S60's rather cramped driver footwell encourages - the system never engages. This rather defeats the point of having it."
I have the same habit but it doesn't defeat the point at all. It gives me full control over whether to let the engine stop or not. If the traffic lights have just changed to red when I stop, I put my foot on the brake, put it in neutral and take my foot off the clutch and the engine stops. If the lights are probably about to change to green when I stop, I keep my foot on the clutch and the engine keeps running. Complete control.
Mines a BMW 118d rather than a Volvo but it behaves the same!