gymratluke

I bought my 01 CLS back in November and the reason I got it was because it was rated to have pretty decent fuel economy(21-28) yet I have only gotten 20.5mpg MAX. My fuel pump relay went out a couple weeks ago and I replaced it right after filling up my tank. Normally my gas light is on around 270-290miles and now Im at 300 with a quarter tank left. I have not done any extended HW driving or anything. Actually I've driven it a little more rough and more in the city then normal. So now Im quite confused as to how my fuel econ has gotten so much better. Normally I'd just be happy and not ask any Q's but Im in the process of trying to find a new car cause 19mpg is not cutting it. If Im gonna be getting over 20mpg regularly I will just the thing but if not its got to go. Thanks to whomever replies!