| But back to the original question. I'd say yes you can. If your on the daily commute and in heavy traffic, you can plan ahead so you hit the next set of traffic lights as they turn green etc, saving fuel for when you're on the open road and want a little more 'fun'
Coming home from work on the M1 you usually hit almost stationary traffic at J33, so its not worth bombing down the outside lane at 70+ as its quicker to just to sit in the left hand lane doing 40-50 (with the flow of traffic) until you hit the tail back | 
