A function on my site is replacing all spaces in my friendly URL's to "+".
So an article named: "best cars 2014", becomes "www.example.com/best+cars+2014".
Is this negative for SEO? E.g. would this be better: "www.example.com/best-cars-2014"
I'm not talking about readability, but am wondering if Google sees/treats URL's with a "+" separator as something different than with a "-" separator?
ps. I can change the working of the function ofcourse, but it has been doing this for a long time, so I would have to start doing a lot of 301 redirects, which I'd rather not.