Under the new standard, the national fleet mileage rule for cars would be roughly 42 miles a gallon in 2016. Light trucks would have to meet a fleet average of slightly more than 26.2 miles a gallon by 2016.
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The current standards are 27.5 miles a gallon for cars and about 24 miles a gallon for trucks. The new mileage and emissions rules will gradually tighten, beginning with 2011 models, until they reach the 2016 standards.
The auto industry is not expected to challenge the rule, which provides two things they have long asked for: certainty on a timetable and a single national standard.
The lack of certainty has been a major issue, providing a disincentive for firms to engage in R&D.