If most of our modern technology?

Question

came from back engineering crashed alien spaceships, why then don't we have cars and trucks that can travel 10 billion miles on a single tank of gas yet?

Answer 1

I guess our engineers have not engineered back that far .

Answer 2

Because the technology was old and broken when we found it, and thus we did what we could?

Or Earth doesn't have the appropriate compounds and elements needed to create those super machines?

I dunno.

Answer 3

Our technology did not come from alien spaceships (for the most part).

People just come up with ideas, and some technology is even discovered by accident.

Answer 4

Maybe because the aliens hadn't perfected the process yet. After all, they crashed, didn't they? Perhaps they ran out of gas.