rendelharris Wrote: ------------------------------------------------------- > DulwichLondoner Wrote: > -------------------------------------------------- > ----- > > > Yes, but if driving at 30mph lets you spend > less > > time at red traffic lights, then you'll be > > polluting less. Also, small differences add up, > > once multiplied by the number of drivers in > > London. > > Is there any evidence that at 30MPH you'd be > avoiding red lights? Surely you'd just be > arriving at the next red light more quickly and > spending longer with the engine idling, having > used more fuel to get up to 30MPH before braking > again. If the lights are synced for 20MPH flow, > 20MPH will be the best speed at which to take > them. There is no reason to think that driving faster means avoiding red lights.