Salesforce Forecast Type: Product Family Quantity/Unit

A company that sells vehicle is using Salesforce to keep track of their sales.
Each of their product (ie: Camry, CRV, etc) is grouped under different Product Family (ie: Toyota, Honda, etc).
Forecast can create a view against Product family to generate a view on total unit sold for each brand.
An example of how the Forecast view look like:
Product Family Qty