I've seen two schools of thought on leasing. The first is to negotiate the entire deal, from the capital cost, which you can lower, to the money factor and residual, which you generally can not raise.
The second is only to negotiate the monthly lease payment amount, as that is the number that really matters.
I like to know how all the numbers work, so I belong to the first school. No sarcastic remarks about how I flunked out of that school, too.