For what it's worth, Hasbro made some 1/6th scale vehicles back in the 60's for the original GIjOE line. the 11.75 inch tall Joes had of all things, a Jeep, a Panther Jet, 3 different Helicopters, a Submarine, a Mercury era Space Capsule, a Hang Glider, a 6-wheel ATV, an 8 wheel Mobile Support Vehicle, and more! So the scale, may not be 'exactly' 1/6th, but was large enough for these big Joes. There was even a line of tanks, mine sweepers, motorcycles, and DUKS, made by Irwin. Amazing how many of these 'big' toys are still around.
A fan film I'm attached to is working on a 1/6th scale X-wing, but it will be a crashed one, used for a force perspective shot.
Jim