
Its in the news, its in the papers, its there everywhere. Everyone is talking about the fuel crisis. Be it the farmers in France, or the daily commuter in Mumbai, everyone is affected by it. With rising crude oil prices, Oil companies around the world have no option other than raising the fuel prices. This invariably leads to a price hike in all commodities, but the consumer in pinched directly by the money he has to shell out to fill his car’s gas tank.
Fuel Efficiency in cars has been talked about for a very long time. The situation is getting worse everyday. I stay in Bangalore, the silicon valley of India. The city is known for its traffic snarls, traffic jams and unruly driving. With the number of cars increasing day by day, there is no respite for the commuter. A distance of about 10 kilometers takes almost an hour in peak hour traffic. This slow moving traffic has its effects on the vehicle’s fuel consumption. Invariably all vehicle owners start complaining about their cars, with some people even taking the issue to the company itself. One cant blame the manufacturer though.
As mentioned in the previous post, companies usually quote figures of fuel efficiency for city and highway driving conditions. These tests are often carried out in very ideal conditions. There are no passengers, no luggage in the boot, and the cars tested usually have minimal equipment. So, in real driving conditions, one should expect something lesser.
There are a few reasons as to why fuel efficiency decreases in real driving conditions. First and foremost reason is the idling time. Now, the engine keeps running during idling, say at a traffic light, or in a traffic jam. Thus, a minimal amount of fuel is fed to the engine, and this is never used for any useful running. Thus, idling is just a waste consumption of fuel. One may burn fuel continuously for a minute or two without actually runing any useful distance.
Driving styles also play an important role in increasing or decreasing the fuel efficiency. A very smooth driving style definitely increases the fuel efficiency. By smooth driving, i mean avoiding sudden bursts of acceleration, sudden braking, and driving at low rpm (revolutions per minute). It is always advisable to drive in a low rpm range. As the rpm increases, the number of times the piston reciprocates in the cylinder increases, and thus also increases the number of times the intake valve opens every minute. As the valve opens more times in a minute, the amount of fuel supplied to the engine also increases. So, say in case of a manual transmission, it is advisable for the driver to use the next higher gear for the same speeds, thus driving at a low rpm. For example, instead of driving in third gear at 4000 rpm, one could rather use the fourth gear at a lower rpm of say 2500. In cars, which do not have a tachometer, and one cannot see the rpm, it is advisable to run the vehicle such that the engine noise is less. If the engine roar increases, it means that the engine is running at a high rpm range, and is consuming more fuel than required. Well, youngsters may say that there is no fun driving at low revs, as performance is hindered, and one cannot show off that cars power. But then, one has to choose between performance and efficiency. There has to be a compromise.
Sudden bursts of acceleration also reduces the fuel consumption. It is better for a driver, to smoothly shift through the gears, maintaining low revs. Accelerating as such, reduces the efficiency, as the engine needs to produce more power to increase a vehicle’s speed. Thus, unnecessary bursts of acceleration must be avoided at all costs. A very important point to note here is that, the vehicle spends more fuel in accelerating fromĀ a standstill to a certain speed, than when cruising along at constant speeds.
The next contributing factor has got to be braking. Sudden braking, and reduction in speed essentially reduces fuel efficiency drastically. When the vehicle is running at say 50 km/h, it can easily cruise a distance of about 100 meters without a significant reduction in speed if the foot is taken off the throttle. Most of the cars made today, have sufficient cruising power once the vehicle is at a particular speed. So, lets say, a driver spots a traffic light around 200 meters down the road, it is better for him to take his foot off the throttle, and let the car cruise the distance and finally come to a stop. Keeping the foot on the gas, till the very end is really a waste of fuel, and doesn’t save too much time as well. In the end, one still has to wait for the traffic light to turn green to start moving again.
In short, to improve fuel efficiency, just follow these simple steps
- Drive as smooth as possible
- Avoid Sudden bursts of speed
- Drive at low revs
- Avoid sudden braking
- And minimize the time you spend on the throttle.

Well, one may ask, “Is this really possible in city driving conditions?” or “All this is a matter of no significance, as the traffic situation is pretty bad, and cant follow these steps.”
To answer these questions, let me share my own experiences.
I took it up as a small experiment to study the effects of driving styles on the fuel efficiency of a car. I drive a Honda Civic Automatic, and a car like this is not very fuel efficient on Bangalore roads. So, i filled up gas in the tank, and made it a point to drive as aggressively as possible in the first week. I used to drive during peak hour traffic both in the morning and evening. I made it a point, to accelerate as hard as possible, brake as late as possible, and drive at very high rpm with the engine roaring just to show off. At the end of the week, the car gave me a range of about 240 km on a full tank of fuel.
Then i made it a point to drive as smooth as possible. I tried to follow my own advice. Well, driving was a bit boring, and not ‘fun’ at all. But at the end of the week , i noticed that the car gave me an astonishing range of around 300 km on a full tank of fuel. Well, thats a big increase. Then, i just drove normally following the regular traffic and ended up with a range of about 270 km.
So, try driving as smooth as possible, and see the change for yourself. Well, after all you could drive into the gas station with lesser money in your pocket and still maintain the same running.
Drive Safe !!
Cheers