Auto Manifesto

July 17, 2009

42 MPG, Not That Hard

Been on vacation for a while. Drove my Mom to upstate New York to visit family friends. We took her '04 Corolla. My Mom has driven Corollas for a long time. She buys one new, drives it into the ground and then repeats the process. It takes a long time.

I drove the whole way and averaged 42.4 mpg, using 18.3 gallons of 87 octane gas over 776 miles. Much of the time the air conditioning was on and the weather was great. Tire pressures were 32 psi, ambient temperature about 75-80 degrees F, humidity fairly low (probably about 30% to 40% max), and cruising speeds in the 60 to 65 mph range.

The car is pretty good for the money. It's a real car that can be found anywhere - not experimental or far fetched in any way. Amazingly, it only cost $1,000 more than the same model my Mom bought 10 years before. Much of this cost containment was achieved by using lower grade materials (interior trim, upholstery, etc). The older model had 4 wheel independent suspension, this one has a rear beam axle. You notice these things.

The ergonomics border on terrible, and the Corolla chief engineer alluded to this when the 2009 model debuted. The steering wheel is too far forward and does not telescope. It does now on the new model. The seat also left my backside numb after an hour or two. There's also a lot of buffeting when behind large vehicles at speed.

It's hard to believe that Toyota could nail it for so many years and then not do such a good job on this one. But overall it is still a good value. The car has been bulletproof as far as reliability.

A Prius is easily $7k more. Unless you drive a lot and fuel prices rise astronomically (to about $9/gallon, assuming 50 mpg for a Prius, 40 mpg for the Corolla, 15k miles/year, and you keep each for 10 years) you will never actually save money.

Automakers could probably gain another 10% in mpg for $1,000 or less. Here's what I would consider:

1. Lower seats and roof to reduce frontal area and aero drag. Everything else constant, a 2 inch height reduction would cut drag about 3% to 4% (likely about 1.5% to 2% mpg improvement).

2. Cooler glass and less of it. AC could then be downsized, and it wouldn't have to work as hard to cool the cabin.

3. More gears. Everyone's already doing this. Four speeds is not sufficient for keeping the engine in its sweet spot over rolling terrain at speed.

4. Predictive cruise control. Cruise control is pretty efficient compared to humans. It would be even more effective if the driver could set a speed band (maybe 5-7 mph) and GPS could let it figure out how to anticipate road grades.

A 10% improvement in fuel economy and $1,000 price premium would result in break-even on savings when fuel is at $2.94/gallon or higher, given the above example with the Prius. It almost makes financial sense at this mpg strata. It would definitely be positive for vehicles in the 25 mpg range.

By the way, this reminds me of my '89 Civic hatchback in college, one of the best handling cars I ever drove. It had a 5 speed manual, enormous trunk space, and it rarely returned LESS than 40 mpg.

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