by John DeCicco
From the time the first hybrids hit US roads a decade ago, some hybrid owners have complained about not achieving advertised MPG numbers. The latest huff involves some disgruntled Honda Civic Hybrid owners acting on that all-American maxim of “Sue the bastards!” Last week, Honda proposed to settle the resulting class-action lawsuit, which would reap a cash windfall for the instigators and a bigger bundle for their lawyers. As a Civic Hybrid owner myself, I just shrugged when their legalese showed up in the mail.
I’m not a hyper miler, and no, neither do I get real-world mileage as high as the original 2003 Civic Hybrid’s window sticker ratings of 46 city and 51 highway MPG. But my wife and I kept careful gas logs since acquiring our hybrid, counting ourselves among the earliest of its early adopters in late March 2002.
Apples to Apples
We also ended up keeping our 1997 Civic LX sedan. That car, now fondly known as the “beater,” had sticker values of 32 city and 38 highway and we kept pretty good gas logs on it, too. Thus, we have close to an apples-to-apples comparison, both being 4-door sedans with 5-speed manuals and air conditioning. We drove the two cars fairly interchangeably, predictably favoring the newer and nicer model for longer trips, although always using the beater for the 90-mile round trip to the airport when leaving a car for several nights in a parking garage.
So what kind of tale do seven years of gas logs tell? As shown on the graph, the Civic Hybrid averaged 42.2 MPG. That’s 12 percent lower than its original EPA composite (city-highway average) rating of 48 MPG. But it’s a 30 percent improvement over the 1997 Civic LX’s average of 32.5 MPG, that latter value being only 6 percent lower than the older car’s 34.4 MPG average sticker rating.
Honda claimed “up to a 30 percent improvement in fuel economy” over other Civics according to a brochure from the time of the Civic Hybrid’s launch. Our observed mileage matches that efficiency gain dead-on even though it falls short of the original EPA numbers. Our main mileage-related complaint is the dashboard fuel economy readout, which gives numbers 3-4 MPG higher than reality. Honda acknowledged this bias and fixed it in later versions of the vehicle, though it leaves early Civic Hybrid owners such as ourselves reliant on gas logs (based on presumably accurate odometers and filling station pumps).
The EPA has since adjusted all MPG label values downward by varying amounts, docking the Civic Hybrid by 15 percent, for example. Applying EPA’s new formulas to our cars, the composite ratings become 30 MPG for the 1997 Civic LX and 41 MPG for the 2003 Civic Hybrid. Our gas logs beat the new EPA numbers for both cars, though by a bit more for the older vehicle.
Within the Probable Range
It’s natural for the most efficient vehicles get the most scrutiny on fuel economy. It turns out, however, that mileage-rating inaccuracies are much worse for gas-guzzlers. The consumer fuel use data collected through the “YourMPG” feature on the FuelEconomy.gov website show that nearly one-quarter of consumers driving vehicles rated at 20 MPG reported real-world values of 14 MPG or less. Over a year with 12,000 miles of driving, that corresponds to excess fuel consumption of more than 250 gallons. By comparison, the 12 percent shortfall of our Civic Hybrid compared to its 48-mpg average label translates to an extra 35 gallons of gasoline over the same distance.
In fact, over all the thousands of YourMPG readings analyzed, the reported mileage has a statistical variation (based on the standard deviation) of plus or minus 33 percent compared to window sticker values. Our Civic Hybrid’s mileage wasn’t nearly that far off, and the low-30’s MPG range reported by the folks who sued Honda falls within the probable range of MPG discrepancies expected for any vehicle.
Beyond the averages, our gas log graph also reveals how much mileage varies in the same car with the same drivers. A seasonal pattern is also apparent, with fuel economy averaging about 3 MPG higher in summer than in winter for both cars. However, the long-term fuel economy is stable; while the gas log plot certainly bounces around, there’s no evidence of a drop-off through time. That’s a notable point for the hybrid, which shows no degradation in average gas mileage over the 7 years and 75,000 miles we’ve driven it.
So where does that leave us? Perhaps we just need to keep in mind another maxim that any all-American should know. Whether it comes to dating or driving, “Your mileage may vary.”
Contributed by John DeCicco, senior lecturer at the University of Michigan School of Natural Resources and Environment. He is a pioneer in developing consumer-oriented automotive eco-ratings as the creator of ACEEE’s Green Book and as designer of the Yahoo! Autos Green Ratings.