Part of the problem is the EPA test's 55 mph highway segment. What's good and acceptable there is horrible at 70+ mph. Even the new test, with its higher speeds, doesn't solve that, because it gets averaged with the old 55 mph test for the final number.
As long as we have these tests, automakers are going to build for the test. Example: Mazda has auto-stop technology available, but it doesn't help on the EPA test. They've decided against selling it. It's a cost to them, for no gain on the test, even though it would save drivers a bunch.
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