I want something a bit bigger i am always traveling and even with the seats down i struggle to fit all my luggage and my girlfriends luggage.

what can i get for 45000 pounds that will be bigger but possibly a bit sporty

I am not sure about the price, but if you like BMW already, and need more room, I would highly suggest the BMW 335i. This car comes in both coupe and sedan form, and is available in RWD or AWD!! IT has 300hp and is very quick. IT has much more room than the M3!

No. keep it and buy something that fits your lifestyle. If you get rid of this car, you will regret it, and want it back everytime the weather is nice.