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the new 3.5 ecoboost engine is something worth bringing up in this context....I'm not sure if the 3.7l NA is also direct injection?



It's a great example. The 3.7 n/a motor gets better economy than the 3.5 ecoboost...

http://www.ford.com/trucks/f150/specifications/engine/

You don't turbocharge engines for a fuel economy improvement. If you did, manufacturers would have turbos on everything...

'18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118