On the highway there are two or more driving lanes. Driving on the left lane is the system prevailing in Indonesia, Singapore, Thailand, Malaysia, India, UK, Australia, and other contries. In this system the slowest lane of highway is on the left, the fastest lane is on the right. On the left lane is for buses, trucks, pickups, on the right lane for small cars (sedans, jeeps, minibuses, etc).
This article is targeted at countries where driving takes place on the left. For countries where driving takes place on the right, the words 'left' and 'right' may have to be interchanged.
To save fuel, the best lane is at the left, or lane for big vehicles. This is due to reduced aerodynamic resistance as air is cleaved by large vehicle in front of you.
This theory was proven by Mythbuster a television show from Discovery Channel that driving behind the truck can save fuel by about 10%. It could even reach 40% if the distance is very close, the show is: Drafting behind a big rig will improve your car's fuel efficiency.
I often use this method to get better fuel efficiency when driving on highway from Jakarta to Bandung via Jakarta Outer Ring Road, Cikampek and Purbaleunyi (Cipularang).
Below is procedure that I use for drafting a large vehicle (truck, trailer, bus):
· Find a big vehicle that runs about 60-80 kmh (37-50 mph).
· Make sure brake lights on the back of that big rig is working properly and clearly visible to you.
· Choose a truck equipped with a low rear bumper, in order to reduce risk and prevent your vehicle get under that truck if that truck brakes suddenly (hopefully not).
· Make sure the truck is driven with steady pace, not oftenly brake and increase speed.
· Make sure the truck driver doesn’t like to change lane or zig-zag.
· Follow the truck with a distance of 2 seconds behind, or about 33 meters behind the truck at a speed of 60 kmh, and about 44 meters behind the truck at a speed of 80 kmh. Distance of 2 seconds is the recommended safe distance to ensure you can react if the truck in front of you brakes suddenly.
· Make sure the truck is not smoking excessively and allow you and your vehicle get enough oxygen.
· Make sure there is no risk of load fallen from that big vehicle.
If viewed from safety side, drafting behind a big rig has the risk that the big rig driver cannot see your small vehicle behind, so there is the possibility that big vehicle brakes suddenly without taking into account the existence of a small car behind. But because of big vehicles have a longer braking distance, the risk of sudden braking effect or sudden stop may be smaller than if a small car brakes suddenly in front of your vehicle.
When in line to pay highway ticket, I also like to use the queue line of trucks and buses. This is because trucks and buses queue looks longer, but the actual number of vehicles is less since a very long truck body when compared to small cars. The length of a truck can be proportional to the length of 2 or 3 small cars. A 50 meters long queue of small cars can be composed of approximately 10 units of small cars, while 50 meters long queue of trucks consists of only about 3-5 units of trucks. Also truck drivers usually have already prepared cash to pay ticket, especially if they are assisted by helper to prepare cash for payment, so payment process can be faster than small cars. So the queue line for large vehicles to pay highway ticket can be faster than queue line for small cars. Currently in Indonesia there are no regulations that prohibit small car get into truck queue when paying highway ticket.
If you are not sure of the safety when drafting behind the truck, then lined up in a small car lane can also save fuel, although less efficient than drafting behind large vehicle. If the highway is composed of 3 lanes or more, then you can choose the middle lane, where many small cars line up. If you choose the right lane then you have to drive your vehicle faster as the right lane is for faster vehicles. Driving at high speed will waste fuel.
So always use the lane that suit your speed, needs, and destination. Drafting behind other vehicle will save fuel, especially when drafting behind a large vehicle. Always line up orderly and ensure the distance to vehicle in front you by 2 seconds rules.