Conditional auto-population, summarize data?
 

I want to make a worksheet that will summarize the data from two spreadsheets, called "cars" and "parts", which have three columns each, one for description, one for SKU, and one for quantity.

I'm trying to make a third worksheet display only those rows with a quantity of greater than 0. I want to split the third summary worksheet into two vertically split sections, one for cars, one for parts. I need to subtotal the "parts" and subtotal the "cars" sections, and then make
a grand total.

I want this to be a dynamic worksheet, so if you change the quantity of a line item in "cars" or "parts", it will automatically show up in the third summary worksheet.

Please help! This has been driving me nuts for a while now. I don't even know where to start, is it macros, VB script, or simple fuctions that can save me?