You've been waiting in a traffic queue for several minutes. What should you do if it's clear that you won't be moving soon? You've been waiting in a traffic queue for several minutes. What should you do if it's clear that you won't be moving soon?

• Possible answers:

   
• A. Keep your engine at tick-over speed
• B. Rev your engine occasionally
• C. Switch off your engine
• D. Run the engine at a constant higher speed