[brandmeyer]

You just compared fleet average in one time period to an extreme outlier in another time period.

In reality, fleet average fuel economy has been nearly flat for four decades, with the biggest periods of movement being driven by brief excursions in the price of crude oil. Those efficiency excursions were in turn driven not by technological improvement, but by changes in the makeup of the vehicle fleets themselves (lighter cars, smaller engines).

https://en.wikipedia.org/wiki/Corporate_average_fuel_economy

[keymone]

and here we're comparing "average" of supersonic flight half a century ago to a potential future outlier. i don't think i'm being outrageously unreasonable here.

[opencl]

The Concorde is not "average", it is the most fuel efficient supersonic aircraft to date by a huge margin. Yes it's kind of old but I think you are dramatically overestimating how much aircraft turbojet engines have improved in the past 40 years.

[gsnedders]

While Concorde was efficient at supersonic cruise, it was ridiculously inefficient getting there (and this was one of the main arguments for the proposed Concorde B).

Also note most aircraft capable of supersonic cruise nowadays don't use turbojets, they use low-bypass turbofans (mostly around 0.3:1).

[keymone]

turbojet is not the only thing that can be improved to reach the overall 10x.