Why Toyota constantly improving the Prius' fuel economy is something of a fool's errand

Toyota has a great marketing line when it comes to the power of hybrids: "Toyota estimates its hybrids have saved their owners more than 3 billion gallons of gasoline worldwide compared to gasoline-only powered vehicles." We're not going to quibble with that number – it is impressive – but it did raise some questions. After all, if Toyota is really interested in saving billions of gallons of gas, then shouldn't the company try to improve the bottom, and not worry as much about the top?

Americans would save a mind-boggling 29.6 million gallons of gas a year if Toyota improved the Camry by five mpg compared to the 3.7 million gallons a 55-mpg Prius would save.

After all, we recently heard Satoshi Ogiso, managing officer for Toyota Motor Corporation and an engineer who has been involved in every iteration of the Prius, say something curious. While talking about how the second and third generations of the Prius have each beat the model that came before by around 10 percent on the fuel economy front, he said, "The challenge to improve at this rate, to beat your own record, becomes very difficult, but all the more motivating. I can tell you we are very motivated to beat our record." So, we asked Ogiso a simple question: "Would it be harder or easier to make, let's say, the Camry, get five more miles per gallon than the Prius to get five more miles per gallon?" He gave us a simple answer: it is "probably a little bit easier for the Camry."

With this in mind, let's look at the numbers. In 2012, Toyota sold 404,886 Camrys in the US, compared to 147,507 Prius models. The 2013-model-year Camry gets a combined EPA rating of 28 mpg, while the Prius Liftback gets 50. The average US driver puts almost 13,500 miles onto their car in a year, so if Toyota were to turn the 28-mpg Camry into a 33-mpg sedan, each car would save 73 gallons of fuel a year, on average. Turning the 50 mpg Prius into a possible 55-mpg Prius would mean each Prius burns 25 fewer gallons a year. When we throw in sales rates, Americans would save a mind-boggling 29.6 million gallons of gas a year by improving the Camry by five mpg compared to the 3.7 million gallons a 55-mpg Prius would save. And, remember, Ogiso said that saving 29.6 million gallons would be easier than working so hard to save "just" 3.7 million. We've got the math below if you want to take a look.



There's a lot of ways to adjust these numbers (the different Prius models are all lumped together in the sales figures, even though they have different fuel economy ratings) and we're only taking the US into account. Also, to be fair, this is an argument that we could make against any automaker, but the general point holds true. Toyota would have a much bigger actual, real-world fuel efficiency impact if it improved its bottom end instead of focusing on the top. Obviously, being the mpg leader has its PR benefits and there are a million other factors to consider, but we were still curious what Ogiso thought about these numbers. After all, as of January of 2012, Ogiso was put in charge of improving some of Toyota's conventionally powered vehicles, in addition to his work on hybrids.

"Of course we concentrate on improving the new-generation Prius," he said. "At the same time, we pay attention and effort to the conventional Camry. If the Prius customers stay in the Prius and the Camry customers stay in the Camry, [your] calculation is right, but thinking about the Camry customer moving into the Prius, that would result in more [fuel savings]." Ogiso admitted that 250,000 people moving from the Camry to the Prius is an unlikely swap, but some consumers do make the leap.

Ogiso also said he has work to do. "Inside Toyota, the hybrid group members have a good performance, a [better] way of improving mpg than the conventional powertrain. The first year I joined the conventional powertrain development, I was so surprised at the difference. So, I am trying to accelerate the improvements of the conventional powertrain mpg." We will be watching to see the results.

Our calculations:

• 13,500 miles divided by mpg = gallons used per year

• Current Camry: 13,500 / 28 = 482 gallons
• Current Prius: 13,500 / 50 = 270 gallons

• +5 MPG Camry: 13,500 / 33 = 409 gallons, which represents 73 gallons saved per year
• +5 MPG Prius: 13,500 / 55 = 245 gallons, or 25 gallons saved

• 404,886 Camrys sold in 2012 x 73 gallons saved per year = 29.6 million gallons saved
• 147,507 Priuses sold in 2012 x 25 gallons saved = 3.7 million gallons saved

* some figures rounded