Introduction to
Energy Efficient Cars

Energy Efficient Cars

Who wants to get the most out of their money spent on fuel? The car ratings on this page show a ranking of the most fuel efficient vehicles. This is where the efficiency of a hybrid can be directly compared to an electric car. The efficiency of an electric car can also be directly compared to the efficincy of a heavy-breathing V-10 gas engine. This is also a way to find out just how economical that economy car really is.

All costs of ownership aside, we want to know what cars give the most bang per gallon. It doesn't matter if that bang is gas mileage, big torque or something comfortably in between. Efficiency can be increased with superchargers, turbochargers, and hybrid systems. Another thing to look for in an efficient car is curb weight. The lighter the car is the greater the potential for efficiency. F=MA (Force=Mass x Acceleration). Reduce the mass and reduce the force needed to accelerate. Or reduce the mass and increase the rate of acceleration using the same force.

The Efficient-Mileage rating chart reveals many different things all at once. The first thing to note is that there are high mpg cars and low mpg cars evenly distributed throughout the list. This confirms that efficiency and high gas mileage are not the same. The most fuel efficient cars are the green cars at the top. Some of these fuel efficienct cars are hybrids, or purely electric, or have a heavy breathing V-10 getting 17mpg. Wait! What?! Why are there so many big engine sports cars among the hybrids? Simple. All gas engines lose a similar amount of energy through cooling systems, and other parasitic losses such as steering pumps, alternators and transmissions. These parasitic losses affect the larger engines much less than the smaller ones. A large engine doesn't have to work as hard as a small engine to accomplish the same task.

Notice the price tags and performance specs. The Corvettes, Vipers, Porsches, Bugatti Veyron, Nissan GT-R, can all out-accelerate, out-stop, and out-corner most everything else on the list. The mpg on these cars is low. However, these cars are finely tuned instruments that use every bit of energy provided. The competition between these cars is very high. Enough research and development has made them just as efficient as the best hybrid cars (I'm excluding all SUV Hybrids here). If you click on the "0.25 mile time" column so the shortest times are at the top, you'll see the top three fastest cars on the list. In first place is the $1.5 million Veyron followed by the Saleen S7 and Ferrari Enzo. Note the efficiency rating. Then note the mpg. The Veyron and the S7 can accelerate faster than the Enzo. The Veyon and the S7 also have higher mpg. The Veyron and the S7 do more with less. This is what efficiency is. The efficient-mileage rating system shows us which cars do the most work with the least amount of energy.

At the very bottom of the list are three Korea-made cars; Kia Rio, Hyundai Accent, and Chevy Aveo. All three of those have the most offensively inefficient engines that are disguised by 27 to 30mpg. The Rio, Accent and Aveo should be getting 40mpg just to be average in efficiency.

The '06 Ford Escape makes its rank among the most offensively inefficient vehicles followed by two more Korea-made cars (Kia Rhondo and Hyundai Tiburon). The Ford King Ranch Expedition is plagued by an underperforming engine and by being the heaviest vehicle on the chart. Only a hundred pounds lighter than the King Ranch is the Toyota Sequoia. The Sequoia is graced with a much more efficient engine turning out better mpg and faster acceleration. The Hybrid Tahoe has a short gain in efficiency over the Sequoia. If the list is sorted by "vehicle efficiency rating" so that the order is from least to greatest, an obvious trend emerges. Of the top ten worst, seven are SUVs (there are nine SUVs in the chart). The others are the Ferrari Enzo, Kia Rhondo, and Rolls Royce Phantom. The Phantom has a nice engine and too much weight. The Rhondo and Enzo must be flushing fuel out the exhaust. The seven SUVs all suffer from towing around their own weight. The Tahoe Hybrid escaped by four places on the chart. The most efficient SUV on the chart, the Ford Escape Hybrid, is just a little more efficient than the average new car. This is why I won't waste much time on SUVs or pickups.

The column titled "Bang per $ rating" shows how much car we're getting per dollar spent. Of course everyone may write this equation differently depending on how they value the various performance qualities. The explanation on how this equation was derived can be found on this page. The chart shows that the most fuel efficient cars also provide the greatest reward for the expense paid. This should be expected when an efficient car should do more with less. The various performance qualities on the far right include quarter mile drag time and speed, braking distance from 60mph, and cornering capability measured in lateral force (g) and the maximum speed the car can weave in between cones (Slalom). Generally, as performance declines, so does efficiency. The hybrids are a renegade to this trend. The hybrid efficiency is typically gained at the expense of performance.

The hybrid technology does provide a net gain in efficiency that is evident in the chart. However, hybrids don't get all this extra energy for free. Hybrids typically carry more weight in the form of batteries that reduce cornering and braking ability. Limiting the force put into acceleration means that more energy is reserved for going the distance. There are energy conversion losses. The energy stored in the batteries was once energy in the form of gasoline. The gasoline energy needed to be mechanically converted to electrons. When that electrical energy is released it is converted back into mechanical energy. The best-case scenario is about 85% efficiency at each conversion. Convert X amount of gasoline to stored electrons =0.85X. Convert it back to mechanical energy 0.85X x 0.85= 0.72X of the potentially lost gasoline energy is used. But no system operates at that ideal peak efficiency. Batteries are still very inefficient. Most electric motors/generators don't always operate at an ideal peak efficiency of 85%. The hybrid system must also provide a net gain over the loss of carrying extra weight in batteries. The energy return (net gain) on a hybrid gets much slimmer. The hybrid energy return gains are calculated on the hybrid / non-hybrid comparison page.

Some of the car models are highlighted. These are featured cars that I want to bring to everyone's attention. Car reviews can be found by clicking the model of a car. The cars highlighted in dark purple are a comparison between hybrid cars and their non-hybrid counterparts. The cars highlighted in light purple are intentionally listed as used cars with a bluebook value also highlighted in light purple.

The first two cars I want to bring to everyone's attention are the Cobalt SS turbo and the Civic Hybrid Navi CVT. Both are under $24,000 new, and offer a lot of performance/efficiency for the dollar.

To find out which car companies are doing their homework, click on the "Brand" column title to sort the list by brand. There are a few car companies that make several noteworthy cars. From A to Z; BMW, Chevrolet, Dodge, Honda, Lotus, Mini, Nissan, Pontiac, Porsche, Saturn, Toyota, and Volkswagen. If the other car companies want me to write about their work then they should make more interesting cars.