• 
• 
• --Select Make-- AcuraAston MartinAudiBentleyBMWBuickCadillacChevroletChryslerDodgeFerrariFordGMCHondaHUMMERHyundaiInfinitiIsuzuJaguarJeepKiaLamborghiniLand RoverLexusLincolnLotusMaseratiMaybachMazdaMercedes-BenzMercuryMINIMitsubishiNissanPontiacPorscheRolls-RoyceSaabSaturnScionSmartSubaruSuzukiTeslaToyotaVolkswagenVolvo
• 
• Home
• 
• New Cars
• 
• Used Cars
• 
• Car Dealers
• 
• Buying Guides
• 
• Research
• 
• Community
• 
• 
• 

Mazda MX-5 Miata

In yesterday's column, I got on my soapbox about the difference between a car that gets good mileage and one that's fuel efficient. Basically, the concept was that a vehicle like the Ford Taurus, which weighs in at 4,015 lbs. and gets a combined EPA number of 22 mpg, is actually more efficient than a Mazda MX-5 Miata, which tips the scales at just 2,480 lbs. and gets 24 mpg combined.

Well, after my fumbling attempts to quantify this previously, I put the crack Krome on Cars research staff to work and here's the new, improved formula to back this up: First, you figure the gallons per mile number, to tell you how much fuel it takes to push a vehicle 5,280 feet. Then, you divide by the vehicle's weight to determine how much gas is needed to push one pound of that vehicle a mile. Now, that number can be compared across different vehicles to see how much gas is being used to push the same weight (1 lb.) the same distance (1 mile). The car that uses the lowest amount of gas is pushing more efficiently.

So, the Ford uses about .045 gallons of gas to push 4,015 lbs. a distance of one mile. Divide by the weight of the car, and you get .00001132, which is the number of gallons of gas it takes to drive 1 lb. of the Taurus one mile. (But in the same way a batting average of .300 is called hitting "three hundred," you can drop some decimals and say the Krome score here is 1132.)

To come back to the Miata, well, it ends up with a Krome score of 1680 — and that's not really too good. A MINI comes in with a score of 1227, which reflects the fact that it weighs a bit more than the Mazda (2546 lbs.) but gets much better gas mileage (a combined 32 mpg).

Here are some other interesting numbers, in order of Krome efficiency scores:

Toyota Prius: 657
Ford Fusion Hybrid: 689
GMC Sierra Hybrid: 844
Honda Insight: 896
Volkswagen Jetta TDI (diesel): 910
Lincoln MKS EcoBoost: 1161
Chevrolet Camaro: 1206
Ford Fusion: 1217
Ford F-150: 1253
Lincoln MKS: 1275
Honda Fit: 1296
Toyota Yaris: 1362
HUMMER H2: 1511
Smart ForTwo: 1536
Porsche 911 GT2: 1657
Ferrari 430: 2407

Again, this essentially reflects how much gas is needed to move one pound of each vehicle one mile.

The results are pretty fascinating, especially that H2/ForTwo comparison, which show the huge HUMMER is actually more efficient than the not-so-smartly built Smart. And by the way, the H2 is so big that GM doesn't have to report its mileage, but a quick survey of the online experts indicates it gets around 10 mpg, so that's what I used in tallying its Krome score here.

Now, the name of the game is still, ultimately, to decrease fuel consumption, but these numbers can go part of the way to showing how much is still on the table for a given vehicle. Again, let's look at the H2 and the ForTwo. The reason the latter is less efficient than the former is that the Smart may get a combined 36 mpg, but it only weighs 1,808 lbs. From a physics standpoint, it naturally takes less fuel to move that amount of weight; if the overall Smart package were as efficient as the Honda Fit package, the German city car would get 42+ mpg. Which should be completely doable, because the Fit itself is proof that a car that efficient can actually be built.

And I think that's probably enough math for the day — perhaps the entire year.

Read Part I: Fuel Efficiency Versus High Mileage Ratings 

You know, this column started out as another one of those rants about lowering vehicle weights. That's because Mazda is debuting its MX-5 Miata Superlight concept at this fall's Frankfurt (Germany) auto show, and I was heartened to see a semi-mainstream-ish car get the same treatment as the Lamborghini Gallardo Superleggera. The Miata has never been known for carrying around love handles, but the Superlight drops even door handles — and the windshield — in its quest to drop weight and increase performance.

And I was thinking, boy, wouldn't it be great if this car went into production and were explicitly positioned as a lightweight, fuel-efficient sportscar? Maybe it would be successful enough to get other, bigger OEMs on the bandwagon and serious about cutting poundage from their performance vehicles. Then, who knows, maybe they'd get equally serious about lowering vehicle weights in general.

But then I checked the EPA fuel efficiency numbers. It turns out that the Miata clocks in at 22 city/28 highway. The new Taurus, carrying some 1,500 more pounds than the Mazda, reaches 18/28. The combined numbers were 24 mpg for the Miata, 22 mpg for the Taurus, which, as you'd guess, also holsters a bigger engine.

Now, something is obviously and drastically wrong with this picture. Is the Miata is terribly, woefully inefficient as compared to the Taurus? Or is the Ford some kind of cutting-edge technical marvel that is incredibly efficient in terms of converting gasoline to miles travelled?

Well, it takes some math, but let me introduce you to the official Krome on Cars mileage efficiency score. It goes like this: First, I determine the gallons per mile for a specific vehicle. With the Miata, that comes to about .042, meaning it takes .042 of a gallon of gas to move the Mazda a mile. Then, I multiply that by the weight of the vehicle, around 2,500 lbs., to get a Krome score of 105. For the Ford, it takes about .045 gallons of gas to move a mile, and I multiply that by the two tons of Taurus to get Krome score of 180.

And now we start getting a handle on how efficient, in the true sense of the word, each overall package is. I'll probably do a deep dive on this stuff in the near future, but just looking at the Taurus and the Miata you start seeing the amazing opportunities available throughout the industry. If Mazda could achieve the same Krome score as the Ford, the Miata would be getting a combined fuel rating of more than 41 mpg.

In other words, the new Ford Taurus is, in fact, a cutting-edge technical marvel when it comes to mpg ratings, but that fact is hidden beneath 4,000 lbs. of metal. And that means there's probably a lot more mileage left to be squeezed out of the current industry lineup even using current technologies, provided someone gets serious about it.

Read Part II: Fuel Efficiency Versus High Mileage Ratings