Sentence Correction

Hi guys, I would appreciate a clear explanation on this topic. For each of the following four cases, can you explain what idiom we must use between as much as and as many as?

1- [as much as/as many as] [percent] of [countable]
2- [as much as/as many as] [percent] of [uncountable]
3- [as much as/as many as] [number,e.g 3,4,5] of [countable]
4- [as much as/as many as] [number,e.g 3,4,5] of [uncountable]

Can some expert comment the four cases?
Thanks a lot,
monge

Thanks for your reply. Following your giudelines I could write:

1) ... as many as 15% of my cars
2) ... as much as 15% of the sand
3) ... as many as 3 of my cars
4) ... as many as 3 of the sand ... mmm this does not sound well, probably we can't use a number with uncountable. My question stem was wrong I think. Forget about case 4).

I still have doubt about the number 1) ... as many as 15% of my cars. If as many as refers to 15% then we must use as much as.
Can some expert explain?
thanks

But 4. as many as 3kgs of sand
I suppose this one is correct.