Best In Class Gas Sippers of 2007

If you are thinking of getting a new car and want to save on gas at the same time, you might want to think about buying a used car. After a couple of years, the sticker shock price on cars comes down, so buying a 2007 model can save quite a bit of money. At the same time, you have a car that is almost new. When looking over what is available for the 2007 model year, you might like to know what is the most fuel efficient vehicle in each class. Here is the official EPA list.

For each major class of vehicle, this table gives the make and model (for the 2007 model year) that gets the best gas mileage. It also includes the city and highway mileage estimates for that model.

2007 Model Year Best-In-Class Fuel Mileage

Class	Make/Model	City/Highway
Two-Seater	Mazda MX-5 (manual)	25/30
Minicompact Car	New Beetle Convertible	22/30
Subcompact Car	Toyota Yaris (manual)	34/40
Compact Car	Honda Civic Hybrid	49/51
Midsize Car	Toyota Prius (hybrid)	60/51
Large Car	Hyundai Sonata (manual)	24/34
Small Station Wagon	Honda Fit	33/38
Midsize Station Wagon	Ford Focus Wagon (manual)	27/37
Sport Utility Vehicle	Ford Escape Hybrid FWD	36/31
Minivan	Dodge Caravan 2WD	20/26
Pickup Truck	Ford Ranger Pickup 2WD (manual)	24/29
	Mazda B2300 2WD (manual)	24/29
Van (Cargo&Passenger)	Chevrolet G1500/2500 Chevy Van 2WD	15/20
	GMC G1500/2500 Savana 2WD Cargo	15/20

EPA Fuel Economy Labels

Cars sold in the US are required to display a fuel economy window sticker. This allows consumers to see the estimated mileage per gallon the vehicle gets in both city and highway driving. Consumers can use the information to compare different vehicles. Starting with model year 2008 the format of this information as well as the tests used to derive it have changed. The changes are in response to consumer demand for better information. In particular, the newer tests account for faster driving speeds and greater acceleration. They also take into account usage of the air conditioner and colder outside temperatures.

Looking at the label itself, you can see the two estimates for city and highway driving on the two sides. In the center is the cost of gassing up the vehicle for a year, based on an estimated price of gas and driving distance. Your numbers will be different, especially the cost number. It is hard to get mileage much better or worse than the estimates, but it is easy to drive much more or less than the estimated distance. Also in the middle, below the annual cost of gas estimate, is a bar with a triangle pointing to an overall mileage combining city and highway values. It shows on the left and right ends the range of MPG values for vehicles in the same class, for example SUVs or light trucks. This lets the consumer see how the vehicle stacks up against similar choices.

The choice of vehicle has a big potential to allow you to save on gas. Don't ignore potentially helpful information on the fuel economy labels!

Fuel Economy Triad

All of the factors that govern your car's gas mileage can be broken down into three groups. Your choice of the make and model of car you drive, how you drive and the mechanical condition of your car make up the Fuel Economy Triad. Think of them like the three legs of a stool: all are necessary to support the load. Depending on your individual situation, one or another might be easier to manage, or potentially give a bigger savings on gas. But you should always keep all three in mind.

An example of the driving habits leg is reducing the number of small trips you make. If you are in the habit of driving a couple of blocks to pick up a pack of smokes, then walk instead. Or make one trip per week to the grocery store and buy twice as much instead of two trips. This is not a practical solution for most of us, but if you can move closer to work or find a job closer to home you can save a lot on gas for the commute.

The make and model of car you drive sets your base fuel economy. If you drive a vehicle that gets poor gas mileage you are going to be using more gas no matter what else you do. Of course, there are other reasons besides gas mileage for choosing a vehicle and it is not always so easy or practical to change vehicles.

A car that is not mechanically tuned up and cared for will get worse gas mileage. If the tire pressure is not high enough or you have a roofrack you don't use, you will be using more gas than is needed. Get your vehicle checked up regularly and stick to the scheduled replacement times on components like the air filters. You will be rewarded with a savings on gas.

The leg most commonly overlooked by drivers is their own driving habits. Don't make the same mistake: always think about the whole Triad!

Thinking About Diesel

What are the differences between diesel and gasoline engines? Can these differences help us save on gas? Well, first of all, diesel engines have a higher thermodynamic efficiency. When they burn fuel, they convert a higher percentage of the energy available to useful work. Basically, all else being equal, they get more miles per gallon. However, to get these high efficiencies, they run at very high compression pressures. Because of this they need to be built strong, which makes them heavier. They are also more expensive to manufacture because of the strength requirements. Another feature is that diesels don't need electrical ignition systems, because the compression pressure is enough to cause the ignition. They need complex fuel injection systems though.

One interesting feature of diesels is that they can run on very low quality fuels. Even vegetable oil is enough to run them on. Try that with a gasoline powered car engine!

Velozeta Six-Stroke Engine

Six stroke engines add another two piston motions to each fuel injection cycle to those of the common four stroke engines. Everyday cars and trucks use four stroke engines. These are called four stroke because for each time that a new shot of fuel is burnt, the pistons sweep up twice and down twice, for a total of 4 sweeps or strokes. The four stroke sequence goes like this:

Intake Stroke

This stroke begins with the piston at the top of the cylinder. The piston moves down, opening up space in the cylinder. As it does so, the valves in the head above open and fuel-air mixture gets sucked into the cylinder.

Compression Stroke

When the piston reaches the bottom of the cylinder, the valves close off. As the piston rises up the cylinder, it compresses the fuel air mixture, which now has nowhere to go. This compression primes the mixture for detonation. The stroke ends with the piston at the top of the cylinder and the mixture compressed into the small space in the head above.

Power Stroke

Now the fuel air mixture is detonated by the spark plug. The resulting explosion forces the piston down the cylinder and rotates the crankshaft against any attached load.

Exhaust Stroke

Exhaust valves in the heads above open up, and the piston rises up the cylinder, forcing out the exhaust gases, which are the ashes resulting from the combustion of the fuel air mixture.

Students from the College of Engineering at Trivandrum in India have developed an engine which adds two more strokes after the exhaust stroke. It uses air to scavenge heat from the cylinder and convert it to motive power. This can improve efficiency, because normally that heat is just wasted. The engine is a modified Honda four-stroke engine. After the exhaust stroke, valves open and allow cool air to flow in as the piston descends. The air gains heat from the very hot cylinder which causes it to expand. This heat-driven expansion occurs forcefully enough to actually power the piston down. In other words, there is a secondary, weaker power stroke after the exhaust stroke. On the sixth stroke (which is a secondary exhaust stroke), the rising piston forces the now warmer air out the exhaust.

This engine uses 40% less fuel and can run on normal gasoline.

Gas Sipper Extraordinaire: 8,923 MPG

Can you imagine getting 8,923 miles per gallon?! That is enough to go around the entire planet Earth on about 3 gallons! The Microjoule is a French vehicle designed to run on normal gasoline. It was built as an entry in the 1985 Shell Eco-Marathon, which is a contest to see who can build the vehicle that gets the best gas mileage. It is a lightweight single-seater, so no carrying the kids and the groceries. You can see in the picture that it is about the size of a man. Kind of a driving coffin, if you want to look at the bad side of things.

The Microjoule has a reverse tricycle wheelbase. Three wheels with the point of the triangle towards the rear. No alien technology here, the secret to the unbelievable mileage is the clean aerodynamic shape. Three cheers for French technology! Now if only Detroit had half the brains of the French, maybe the US automakers would not be going down the crapper.

Gasbuddy

In a local area, the price of gas can often be different by up to 20 or 30 cents at different filling stations. If you can find the cheapest one that is not too far away, you can save quite a bit on gas. The problem is how do you keep an eye on all the regional filling stations to know the prices? There is no way that we have time to phone around and ask them all, and if you drive around to see, you will burn a fortune on gas! Fortunately there are websites to help us. One of them is Gasbuddy. Check them out!

Don't Pay for Octane You Don't Need

The octane rating of a fuel tells how resistant it is to "knocking" or "pinging". This happens when the fuel-air mixture in your cylinders explodes before the spark tries to set it off. Early explosions that are not timed exactly to the piston position can rob power from your car. High compression pressures in the cylinder are the cause of early explosions, or preignition. The compression pressure is something that is designed into your engine. So you can use the lowest octane that does not cause knocking. Higher octanes do not give you better performance, because the compression pressure of your engine is fixed. This can save on gas money quite a bit!

Tip: you can mix gas of two different octane levels to get what you need. Imagine that your car needs at least 87 octane, and anything lower will cause engine knocking. If your service station has 85 and 89 octane, but no 87 octane, then putting in the 89 octane will keep your engine from knocking, but you are paying the higher price. What you can do is buy half a tank of 85 octane, and then top up the other half with 89 octane. They will mix to give you the 87 octane that your car needs, but you only paid the expensive price on half a tank!

Maybe Skip the Acetone

Yesterday's post talks about the possibilities of adding acetone to your gas to get better gas mileage. Here is a second opinion. According to Bobby Likis in this video, acetone might clean carbon deposits out of your fuel system, improving the gas mileage a little. However, cars are not designed to use it. Acetone might damage the wiring of the fuel pump or the fuel injector system. Also all of the rubber seals in your car could be damaged. Bobby's recommendation: don't put acetone in your car. Watch and see for yourself!

Acetone for Better Mileage

Some people say that you can get better gas mileage by adding some acetone to your gas. When your car burns fuel, it is actually burning gasoline vapor, not liquid gasoline. If you have ever dropped a match into liquid gasoline, you have seen that the whole thing does not explode. Instead, your car combines gas vapors with oxygen from the air to form an explosive air-fuel mixture. Then a spark from the spark plug detonates this air-fuel mixture, which has enough explosive power to throw the piston up against all the load your car is putting on it.

The idea with acetone is that adding it to gas will make the gas vaporize better, reducing the amount of liquid gasoline droplets that may get into the cylinder helping generate a more complete burn. This will get you extra mileage.

In this video, Dr. vonHypermiler says he uses acetone with no harmful effects on his engine. He puts 2 ounces of pure acetone per 10 gallons of gas and gets savings on gas of 9.64% !

Watch his video and see what you think!