If you have automatically scheduled follow up response mechanisms for email leads, it does not hurt to get leads from a wide area.
If you have to "quote" prices + payments to all on the vehicle they inquired upon (plus one with more equipment, one with less and the closest used one that you have), there is a very real cost to leads that don't close very well - whether due to source or customer location. Your time is not free.
You'll hear more about this at the upcoming Digital Dealer conference in Orlando, but the self-serve nature of a shopping cart for vehices + F+I can relieve this pressure; allowing you to automate everything except the late in the stage "need to / want to talk to a salesperson" part.
As for websites, don't junk them up (especially the home page) with a whole bunch of attention grabbers which don't move to a lead / conversion. Consumers do NOT read a website page. They glance at it and click on the first thing that grabs their attention that seems to be related to why they are there.
Do this test... be a consumer in your local market who wants to buy a car of the brand that you sell... go to your website... start counting to 4... In that much time, did orient yourself and see the call to action that as the site designer you want such a consumer to click on?
If not, what got in your way?
Where did clicking on that call to action take you? Every click a consumer has to take that does not satisfy their primary purpose of their visit results in a 35% drop in conversion. Frustrate me, confuse me, annoy me... Click. Gone.
Your website is not a goodwill / PR machine. Online consumers do not care about anything you have to say beyond their purpose + only want to hear any message like "we are good people" within the context of what they want to do in language relevant to what they want to do. Done any other way it sounds like blah, blah, blah and gets between them and the action you want them to take.
IMO... Click to lead generation as conversion is only one metric to study + is only a guidepost to the more qualitative questions about site design and user experience that you should be asking.
Total cost of activity by source versus gross generated from sales including total time, training and supporting software costs is the more important one. In CPA school we called this ROI and it always trumps activity measurements like impressions, clicks, visits, leads, calls, etc.