Subject: our big SUV mpg
As a failed engineering student, I've always been impressed by the way Toyota engineers can often improve the fuel economy of new-generation vehicles, even when the new vehicles are heavier and/or more powerful than the ones they replace. This is especially true with the big, new SUVs we've introduced for 2008 -- LX 570, Land Cruiser and Sequoia -- which have a 5.7-liter V8 in place of the previous 4.7-liter one.
Comparing EPA mileage estimates between 2007 and '08 models can be tricky because the EPA changed its test for 2008 to better reflect real-world driving conditions. The 2008 test results are generally lower than 2007, even for vehicles that have not changed mechanically.
However, a part of the EPA website -- http://www.fueleconomy.gov/feg/ratings2008.shtml -- allows you to view old/new mpg ratings for a specific vehicle. Using this EPA information, we were able to compare the 2007 SUVs with their 4.7 V8s to 2008 models equipped with the 5.7 V8, using the new test for both, and the results were surprising....
For the Lexus LX:
The 2007 LX 470 was rated at 12 mpg City/15 mpg Highway. The LX 570 mpg is 12/18. Although 18 mpg Highway seems like "only" a 3 mpg gain, it's actually 20% better than 15, which is a significant improvement, especially considering the size and power increases on the LX 570. You may attribute much of that to the new 6-speed transmission being in overdrive at highway speeds.
Maintaining 12 mpg City is also quite an achievement. This is largely due to improved technology in the 5.7 V8, such as dual VVT-i on both the intake and exhaust cams, compared to VVT-i on intake cams only on the 4.7 V8.
For the Toyota Land Cruiser:
The 2007 model with its 4.7 V8 was rated at 12/15 mpg and the 5.7-liter 2008 model at 13 mpg City (an 8.3% increase) and 18 mpg Highway (+20%). Again, chalk it up to the new 6-speed automatic and improved engine technology on the 5.7 V8.
For the Toyota Sequoia:
The improvements were more modest, but still moving in the right direction. The 4WD Sequoia went from 13/17 mpg with the 4.7 V8 to 13/18 with the 5.7 V8, an improvement of 5.9% in highway driving. The 2WD Sequoia goes from 14/17 to 14/19, which is 11.8% better on the Highway. Same new engine/transmission combo.
When you consider that all of these new generation SUVs are bigger, more powerful and have better towing capabilities than the 2007 models, the improvement is rather remarkable. And that's with conventional gasoline drivetrains, not diesels or hybrids.
If this is too much information, I apologize.
Toyota Motor Sales, U.S.A., Inc.
1270 Ave. of the Americas, Suite 1800
New York, NY 10020
212-644-3424. fax: 212-644-4871