Article on Fuel Efficiency - Part II

In Part I, I talked about some of the key factors that you can consider when purchasing a new vehicle, from a fuel-concious point of view. Now, assuming you already made your choice, or, likely, already are driving, we'll need to make the best of what we have. Even before we hit the road, there are a couple of things that can be done to maximize on fuel efficiency.

Here are 6 pointers to keep your fuel costs as low as possible:-

1. Keep your tires properly inflated
Even before you start worrying about how to drive, you'll need to pay attention to your tires. A poorly inflated tire produces more drag, hence, more force is required to overcome the rolling resistance. In the long run, your tires will also wera out faster, so it's a double whammy on the maintenance costs.

2. Remove any unnecessary weight
It takes more energy to move more mass the same distance. So, try to keep your car clean and clear of unnecessary weight (stuff in the trunk, etc.). Note that you should remove "unnecessary" weight only. Do leave the essentials in your car, for example, your spare tire and tool kit!

3. Aerodynamic efficiency
Your car will have a much easier time slicing through the air if it had a sleek profile of a dolphin, as opposed to perhaps the shape of a tractor. So, consider removing roof racks (which you'd probably never ever use) and fancy body kits (especially those oversized rear spoilers). Spoilers and body kits, besides adding weight, ironically serve to provide downforce to firmly plant the car onto the road at high speeds. A lot can be said about this, however, adhering to the topic of fuel efficiency, bottom line is, lose the extra appendages.

4. Smaller and / or lighter rims
As far as tires are concerned, the overall outer diameter of the tire must not change (otherwise your speedometer will be showing the wrong speed). So, as the rim gets larger, the tire gets smaller. Generally, rims are more attractive than black rubber tires, so for aesthetic reasons, people tend to go for larger rims (just watch Pimp My Ride). Unfortunately, the effect of having a larger metal rim is increased weight, which is harder to spin and also to stop spinning (affects not only your acceleration, but your braking as well). Tire size is carefully determined by the car manufacturer (usually) and is matched with the other elements of the car. Sometimes, it varies within different trims of the same model. For example, the Honda Civic FD1 comes with 16" rims, and the FD2 now comes with 17" rims (formerly came with 16" rims, like mine). The Type R, owing to a more powerful engine, comes with 18" rims, while the frugal Civic Hybrid comes with only 15" rims.

5. Air conditioner
OK, this one's tough. Driving around with the air conditioner off is not a great way to save fuel (you'll earn a notorious reputation for being a miser from your sweaty passengers instead). Note that your car acts like a greenhouse, in the sense that the glass traps heat inside. On hot days, the air is actually hotter on the INSIDE of your car. When you first open the door and start the car, it's important to vent the hot air from the car, so that the air conditioner can start to work on air at ambient temperature, which is generally a few degrees cooler. So, leave the windows open and turn on the blower to push all the hot air out (at this point, it's pointless to actually turn on the air conditioner, just running the fan at high speed will do). What happens next? Well, while driving around, one has the tendency to turn the temperature control down and turn up the fan. However, consider the fact that sometimes, the air conditioner is cold enough, just that the cool air doesn't get the chance to circulate throught the entire car. What I do is I try to keep the temperature setting as high as possible, and turn up the fan speed. The fan speed has less impact on the engine than the air conditioner compressor setting. To keep the car cool while driving around, invest in a good windshield tint (that blocks infrared radiation, the source of heat). You'll also want a tint that blocks harmful ultraviolet radiation, and should also allow at least 70% visible light to penetrate (that's the legal requirement here in Malaysia). It's inconsiderate (not to mention illegal) to install really dark tints which block other drivers' view, and it's down right rude to block the windows and rear windshield with screens, towels, etc..

6. Plan your trips
If you refer to Tip #5 above, this doesn't only mean that you plan trips at night for minimal use of the air conditioner ( though it would help if you could do that in practice). In planning trips, one should opt to consolidate several short trips together, so no redundant trips are made. The route that is taken should ideally pass through low density traffic, so to avoid unnessary braking, stopping and accelerating. Avoid areas that contain many speedbumps, traffic lights, pedestrian crossings (such as schools, especially during starting / ending of school hours). Sometimes, using a longer but straighter route that allows for a more constant, uninterrupted drive would be more fuel efficient that going through the shorted possible distance. Where possible consider alternative means of transportation, car pooling or even walking.

Bonus Tip - Use fuel with lowest possible octane rating
This does nothing for fuel consumption - if you make 14km per liter with RON 97, you'd probably have made 14km per liter if you used RON 92 fuel. The thing is, RON 92 is cheaper than RON 97, so the cost per distance will be lower. Assuming your engine is designed for RON 91 and above, it doesn't make any difference if you were using RON 92, RON 97 or Racing Fuel. You may lose some power if your engine can actually advance timing to take advantage of higher RON fuel, but then again, we are focused on maximum fuel efficiency, right? Some people may be skeptical on this, so, to each his / her own....

Well, that's 6+1 ways to prepare your car for maximum fuel efficiency. In my next, I'll share some pointers on what I mean by planning trips and also fuel efficient driving habits.

Previous posts:

• Article on Fuel Efficiency - Part I (Choosing the right vehicle)