This has been my favourite pass-time to look around and find out inefficiencies that are out there and no one takes a notice of that and usually like to play with numbers how by getting rid of small inefficiencies we can make a lot of difference.
First and foremost one of the most common thing that you'd observe that the roads are not laid footpath to footpath (ie. where the footpaths exist), now what happens as a result of this is about 20 and sometimes as high as 30 percent of the road is not usable. Moreover, that also makes it possible for the hawkers to occupy the unused space and further agrravating the problem, if you lay the road footpath to footpath, you create a natural entry barrier for encroachment, because the vehicles start using that part of the road. Furthermore, one may really look at the size of a footpath. There is no real need to have a footpath three and a half feet wide, that only makes it obvious choice for a tapari. Instead if we just have a footpath which is just a little more than a couple of feets, it allows those two extra feets to be used by the vehicles. There is another advantage of laying roads end-to-end, the chances of developing potholes is reduced substantially, because, the rain water flows freely, leaving lesser chances for erosion. Just a small thing can make a substantial difference.
Next is the inefficiency a lot of us indulge in - eg. when we are standing at a signal ie. if we are standing at a signal, and if we know that our turn is going to take something more than thirty seconds, it might be prudent to switch off the engines. This saves a lot of petrol, consider a vehicle, which while idling consumes a litre of petrol every hour. which means 1000ml every 3600 seconds which means 1ml every 4seconds. so assuming you switch off the engine for 40 seconds you've saved 10mls worth of petrol, re-ignition might consume another half ml of it. But even then 5 ml is a lot of saving. Because if 10million vehicles save on an average 20ml per day, it is equivalent to 20000 litres of fuel saved everyday that is a lot. Again, a simple thing that can make a huge difference.
There may be 100s such examples. Actually, I always say this if the efficiency in the world is improved by 50%, we'd have to get rid of 95% jobs in the world. Perhaps, its human society's way of making sure that most of us are employed. :-)