The one big drawback owners of petrol cars face is fuel economy. Diesel cars are at least 25% more fuel efficient than equivalent petrol cars. However, many petrol cars give high “claimed mileage” figures, certified by ARAI, which are pretty difficult to achieve in real world conditions.
Although ARAI’s test mileage is supposed to be reflective of real-world driving conditions, it is tough to achieve the figures claimed in real-world driving. For instance, a Maruti Alto 800 has a claimed mileage figure of 22.7 kmpl – something that is widely advertised and a reason why buyers flock to the car. But in real-world city driving conditions, owners are hard-pressed to get over 18 kmpl, which in itself is not bad. Take a fuel-efficient petrol sedan for instance – the Hyundai Verna 1.6 petrol has a claimed fuel economy of 17.01 kmpl. But real world mileage seldom exceeds 12 kmpl. Also read: How to get maximum mileage from your diesel car
Why this huge difference in fuel economy? The issue is with the nature of a petrol engine, where peak torque comes in much higher than a comparable diesel engine. One tends to rev a petrol engine much higher to get momentum and as we all know revving wastes fuel.
So just how do you drive a petrol car in normal circumstances, without hypermiling to get maximum fuel economy? Here are a few pointers.
Don’t hurry, no worry
Although the whole point of a petrol car is the instant pick up and faster acceleration one gets compared to a heavier diesel, one needs to be very gentle with the car to squeeze out maximum fuel economy. Drive with just about 20% throttle input at the most and don’t press it more than that if not needed. Use the gears to quickly gain momentum.
Don’t wait for peak torque
Logic will tell you that you will get the best fuel economy figures at where the car makes peak torque as well. However, that’s true for when you reach cruising speed only. With a petrol instead, just depend on the linear torque to get you moving. For instance, even if peak torque develops close to 4000 rpm, you will have enough to keep you moving at 2000 rpm on flat surfaces. Shift up early to the next gear, keeping the rpm only around 2000 rpm, which will burn less fuel.
Use engine braking, coast to a halt
Anticipate your stops early. Don’t rev hard and brake hard. Instead, if you are in top gear as you approach a traffic light, just let off the throttle completely. This lets the car use engine braking to slow down and activates the fuel overrun cut-off that most modern fuel-injected cars come with. This will burn just the minimum amount of fuel. Shifting to neutral and letting the engine idle, may burn a little more.
Keep idling to a minimum
Unlike in a diesel car where you need time for the turbocharger to spool down, a petrol car without a turbo is easier to switch off when not in use. If you have to stop for more than a minute switch off the engine to save fuel.
However, the converse is also true. If you have to stop for less than a minute DON’T switch off the engine. The reason is, when you restart the engine, it takes as much fuel as it would consume with 30 seconds of idling.
Reduce load on the engine
Another way to save a bit of fuel is with judicious use of the airconditioner. The AC compressor saps power from the engine. So when you have to pick up from a traffic light, switch off the AC compressor and then accelerate. Switch it back on only after you achieve a cruising speed (of course, that depends on how comfortable you are in summer heat). That way the engine has a lower load to handle and gives better fuel economy.
On the highway, keep the windows rolled up and use the AC – as using the AC actually consumes less fuel than having the windows rolled down as the air resistance increases with windows down and decreases fuel economy. Also read: 10 simple ways to reduce your monthly fuel cost
Other than these specifics, the standard fuel economy tips apply:
Standard mileage tips
- Maintain the optimum tyre pressure, increasing it by 2 psi over normal also helps.
- Reduce the unladen weight in the car, by removing unnecessary luggage
- Get the car regularly serviced, keeping air filter, spark plug, fuel filter and injectors clean
- Gently accelerate, gently slow down
- Shift gears early to increase fuel economy. Drive in the correct gear to avoid flooring the accelerator and straining the engine.
- Drive at the optimum speed, not exceeding about 60-70 kmph depending on the car
- Switch off the engine if you are going to be idle for more than a minute
- Reduce AC use if possible
Driving a petrol car in this manner can increase your fuel economy by nearly 20% and it could give you close to the claimed mileage figures, and probably even better figures on the highway. Share any more tips you have for getting maximum fuel economy from your petrol car. Also read: Hypermiling techniques, how to get maximum mileage from your car