What Fiat / Experts say: 1. Fiat manual / Eco-drive suggests switching off if wait is more than 60s 2. Fiat suggests start driving immediately on switching on, albeit slowly on lower rpm for a few minutes to let the engine warm up. 3. Experts suggest 60s of idling on starting and after halting to let the turbo stop with engine oil flowing. If you follow 1, it can get difficult to follow 3. What I follow with my TJet: 1. I follow Fiat's advice (both 1 and 2). To ensure my turbo is not damaged, I start of slowly, not allowing the rpm to go above 1200 for the first minute. 2. In case there is a long signal, especially when you may have to wait for 3 turns to cross one, I delay switching off only if I have been revving beyond 1500rpm before the signal. Since in most cases I know where this can happen, I plan for it.