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What Affects Fuel Economy?

So you’re looking to buy a new car. As a Filipino worried about the cost of fuel, it is quite natural that one of the most important factors you’re considering is fuel economy.

“I’m going to buy a small car so that I can get good mileage.”

If anything, the results published by DOE and Petron dispels the myth that a smaller car has better mileage. Many factors affect fuel economy aside from the size of the car and engine. There’s the type of fuel, transmission, drag co-efficient, weight, displacement, forced induction or naturally aspirated, to name a few. But based on the study by DOE and Petron, these are the top factors to consider.

Fuel Type

Probably the most influential factor would be either to get a gasoline or a diesel. Diesels are much more efficient simply by virtue of how diesels work. Diesels have a higher compression ratio than gasoline engines. In practice, the difference between the best result for gasoline engines and the best diesel was a whopping 9.32 Km/L. To put that into perspective, with the current fuel prices, if I were to drive 15,000 Km, the average distance I drive in a year, I would have Php 10,666.57 in savings; the same price as a new set of tires.

Transmissions Type

As far as transmissions go, if you read the previous paragraph and are now looking at a diesel, a good old stick shift is still the more fuel efficient option for diesels. (Provided that the driver has the ability to control his/her right foot.) Top 3 diesel entrants in the study were all manuals. Additionally, the Hyundai Accent which had both M/T and A/T entered in the study showed that the M/T variant 3.77 Km/L more fuel efficient than the A/T version.

It’s a different story for gasoline powered cars. If you still value the high revving smoothness of a gasoline engine over fuel economy, take note. The top 5 slots for gasoline powered cars were a combination of CVTs and M/T with CVTs taking the top two slots. This just shows that CVTs has become a proper alternative for hypermiling drivers.

What about Engine Size?

“Surely a big 3.0L engine would use more fuel than a 1.6L!”

Nope.

Even I am surprised to see a pick-up top the Fuel economy test for diesels, but only because of how big the truck is. The Isuzu D-Max with a 3.0L diesel tops the list at 38.46 Km/L with a distant 2nd for the Hyundai Accent 1.6L diesel at 29.41km/L.

For gas powered engines, a Suzuki Celerio with a 1.0L engine took the number one spot with the Honda Jazz 1.5 at a close second. Even if a 1.0L topped it, you do get more car with the Jazz over the Celerio. Having that extra 50% more displacement and 1 additional cylinder at the cost of half a Km/L (0.54Km/L difference) will surely come in handy for overtakes and uphill climbs, not to mention having the extra room for 3 full sized adults in the back.

Recommendations

Based on fuel economy alone, it’s hard to deny that the D-Max is looking like a good pick. However, if a pick-up is too big for a city runabout and not to your liking, the Hyundai Accent diesel is a solid choice. Trust me, I bought one.

However, if you prefer a gasoline powered car, it’s worth noting that the Hyundai Elantra found itself at the 4th spot for gas powered cars; the only compact car in the top 5, surrounded by sub compacts and superminis.

Honda, notably scores the most fuel efficient 4-Cylinder gasoline engine with the Jazz, and the most fuel efficient gasoline powered crossover with the HR-V. Gear-heads will also be pleased to know performance need not burn a hole in your pocket as the Honda Civic RS scored 6th place. This is not a bad result for a performance oriented package.

The most economical 7-seater goes to Toyota Innova with a 2.8 diesel A/T. This beats the gasoline powered Honda Mobilio. On the flip side, it’s hard to ignore the absence of one Toyota Vios. I’m not sure why Toyota decided not to enter their subcompact in the study. But, the equation of their same old power plant in a heavier new body, I suspect, would not bode well for economy figures.

It’s quite difficult to compare economy between diesels and gasoline cars because the former will always have an innate advantage. Also, the high cost of gasoline fuel itself doesn’t help. However, the lower cost of production and subsequently purchase price of gasoline cars might be the deciding factor for some buyers.

References: DOE, TopGear PH

This article was written and contributed by Rey Emmanuel O. Sanchez.

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Rey Emmanuel Sanchez

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3 Comments

Baba says:

8 years ago

Our hyundai tucson 2.2 vgt is more fuel efficient than the innova 2.8 diesel when we had a convoy spanning ~ 100kms with 5 persons riding in each car weighing ~ the same. The innova was about 12-13km/L while tucson was about 19 kms/L.
- Reply
jake franco says:

8 years ago

Am interested in the diesel passenger van category (i.e. toyota commuter, nissan urvan, foton, joylong, isuzu) anything?
- Reply

Rey says:

8 years ago

Unfortunately, the DOE-Petron study included only 2 vans, the Peugeot Expert Tepee and the Nissan Urvan. Between the 2, the french car did more Km/L than the Urvan – 2.54 Km/L, in fact. However, the Peugeot has a tiny seating capacity of 9 compared to the Urvan’s capacity to seat your whole barangay.