How does traffic gridlock affect fuel consumption?

Hi Paul, I work with the CEO Magazine. I am writing about impact of traffic ‘jams’ on fuel economy. How does gridlock affect fuel consumption of cars and does traffic congestion always mean more fuel consumption? Jacobs Seaman Odongo.

Hello Jacobs, the subject of how traffic congestion affects car fuel consumption is a topical discussion.
Generally the faster a vehicle travels, especially during aggressive driving, the more fuel it will tend to consume.
Perhaps that is why vehicle fuel consumption studies base their observations on velocity, acceleration and time to define fuel consumption in terms of kilometres covered per litre.

It is also proven that the slower a vehicle drives in traffic congestion, the more fuel it consumes.
In urban traffic congestion we tend to keep accelerating at high revs because of the stop and go (frequent take offs) situation.

A car travelling through congested traffic will tend to consume more fuel than one which is travelling at constant reasonable speeds.

The critical issue is low gear ratios (gear 1-2) and higher engine revolutions which create a bigger load on an engine and demand on the energy source which is fuel.
Traffic congestion may not always cause high fuel consumption, especially where driver behaviour is modified.

Motorists may choose alternative routes, plan their journeys to avoid getting into traffic gridlocks, out rightly switch off their engines where traffic is not moving for a little while or accelerate more gently at take offs.

Technology can also play a role in reducing the effect of traffic congestion on fuel consumption.
Motorists can chose vehicles with smaller engines and more efficient fuel delivery systems.
For example, a motorist driving a small 1.0 litre petrol EFi Toyota Vitz mini hatch will have less fuel consumption in urban traffic jams than another motorist driving a 3.0 litre petrol Toyota Prado station wagon.

Newer engine technology such as Variable Valve Timing or direct stratified fuel injection and common rail diesel injection will produce more fuel efficient results, even when driving in traffic congestion. New innovations such as the automatic traffic stop start feature in leaving such as VW, Mercedes Benz and BMW.

This innovation prevents excessive vehicle idling and fuel wastage in traffic congestion by switching off the engine when you stop for a while.
Restarting it is by a gentle tap of the accelerator.