Sorry for waiting Lars,I've been off home lately

So,economy picking is sort of sweep picking
BUT it matters only when you go from one string to the next one.
You don't have to play 4-5 strings to do economy.
Basic idea is,if you go from high E do B string you do one upstroke,
not upstroke and downstroke like in alternate picking.
And you do only ONE upstroke to play 2 strings,not two of them.
It's only one motion,like in sweeping,sort of.
Same thing is when you go to the higher string,you do one downstroke.
That would be it.