URL Optimisation how far can you go

How long and keyword heavy can URL's be:

Would this be suitable:
www.xxxx.com/cars/vintage-cars/vintage-cars-for-sale


What if you put keywords in the URL which weren't necessarily the same as the title:

www.xxxx.com/cars/vintage-cars/vintage-cars-for-sale
Title: Vintage Cars for Sale - car interiors

 

Usually two or three keywords are sufficient in your URL

 

too many is like not enough. it should be natural and intuitive

 

Just keep it natural and logical dont keyword stuff it.

 

I think what matters most is back link not really optimizing your url

 

Not agree actually,can't ignore URL's impact in SEO for ranking in SE's.Although long tail URL's looks horrible and hard to remember but may helpful to target keywords if not exceeding the maximum length of characters.