Need to shrink my large if elif statement in python

I trying to see if there is a more efficient way to write if elif statement. Writing an API to generate a url based on the number of parameters the class is called.

For Ex:

def Cars(self, model=null, color=null, miles=null)

    if model == null and color == null and miles ==null:
        url = cars/
    elif model != null and color == null and miles ==null:
        url = cars/model=%s)% model
    elif model != null and color != null and miles ==null:
        url = cars/model=%s/color=%s)% model, color
    else url = someting

    return url

I have more than 10 parameters and don't want to write that many elif statements with all the combinations..