I have a huge set of data for our stores across 3 markets in Nebraska and Missouri. I have compiled this data for fresh, phone, and internet across all lead sources, as well as, fresh, phone, and internet across individual sources. This data covers a wide range of site (FordDirect, Kia Cobalt, Cars, Autotrader, in-house built group and location websites, and other 3rd party lead sources).
This is just from the top of my head, I'll have to pull up the spreadsheets to get more precise data.
The best quality of lead (highest % to convert to sold) is a phone call on used vehicle originating from from our group or location website followed by form submission on used vehicle from our group or location website.
Our lowest quality of lead was used vehicle lead from Autotrader both phone and form leads. All locations ranged from 0% close to 15% close rate, compared to 25-35% of phone and form leads from our websites.
Schedule Test Drive form has our highest show and sold rate on web forms, but also least submitted. Get More Information and Confirm Availability regardless of position are highest submitted forms. I've done a lot of A/B testing of form positions and wording. Regardless of what the open form on upper right corner is titled, it gets submitted the most. I randomly (probably not a great idea) but I titled that form "Give Us Your Information" and it was still filled out at same rate as Confirm or Get More Info were seeing in that opened upper right position.