We can all agree, flying from point A to B, a headwind will increase fuel consumption, and a tail wind will reduce it. The "jet stream" inspires these types of thoughts.
Quartering headwind, crabbing into, still more fuel, right?
Quartering tailwind, probably less, but the aircraft still must oppose the cross wind component with some force which is ultimately derived from burning fuel.
Perhaps, from someone with airliner experience, at what point off my tail does wind stop assisting in fuel economy?
With the tail as 0 degrees, nose as 180, and beam as 90, my guess would be around 80 degrees, a cross wind with a bit of tailwind component.
Is there evidence from practical experience to support or refute this guess?