If it coasts further it helps
. Are you able to see the effects in fuel consumption is a different matter.
I cannot see it in my lupo because I added so many other changes to the car during last tank, but the other guy will not do any other modifications and he will monitior the coasting distances...
If he gets also good results in coasting I will order more and start selling this stuff
.
Basicly you can treat any odject that need to have little friction like your brake calibers to glide better all joints etc...