Increasing fuel mileage by injecting ether.

Dry air is just as good.

Nitrogen is used, because it is cheap and available (already produced),
and is dry. There is little call for "dry air". It's cheaper just to
use nitrogen. Why?

A lot of nitrogen is produced, for the welding industry, and it is inherently
dry, as processing (distilling) removes all the moisture.

Other than that, nitrogen gas no advantage over dry air, and very little
advantage over atmospheric air.

Nitrogen is cheap, convenient, and easy to obtain.
And it works just fine in tires.

 

I actually received ether as anesthesia when I was seven years old.
It was a vivid experience. As I went under, I dreamed/hallucinated
that I was in one of those carts that run on tracks into the mine in
all the cartoons. The track was a huge spiral going down, down, down
into darkness. Then... blackness. Later - how long I could not say -
I was in the same cart only this time I was going up, into the light.

I awoke in the hospital room with a splitting headache. It wasn't an
experience that I ever felt compelled to repeat.