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Sorry, we don't yet have gas mileage data for the Sierra HD.
None of our members have yet commented on the real gas mileage of the GMC Sierra HD.
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Unlike other fuel economy surveys, TrueDelta's Real-World Gas Mileage Survey includes questions about how and
where a car was driven. So you can get an idea of the GMC Sierra HD's
real-world MPG based on how and where you drive a car.