The real fuel penalty is at higher speeds, due to higher revs. Yeah, going 40 mph in 5th rather than 4th (at similar rpm) is not going to matter much. The problem is when you can't shift to 7th
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Do you track your car? I can't imagine running even higher rpm on the highway than already am; 3K rpm at 70 mph in 6th it's just ridiculous on a V8 car, even with a high redline like ours. You're probably turning 3,500 rpm now
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