is it really necessary to warm up my 2000 bmw 323i because it takes abt 7 mins and i think it just eats up gas so is it really necessary wld it hurt the engine in any way if i dont

Your engine (and every other engine for that matter) is designed to work best at a certain temp. When it's cold ( under around 190*F for most) all the little parts in there have either shrunk, or expanded.
The worse time for engine wear is at a cold start up. If you do not let you car warm (until the temp needle at least starts rising) you are putting alot of unnecessary wear on it because of the RPMs, and stress, your putting on the engine during normal driving.
You may not notice any problems right away, but later down the road, when your car starts loosing power and smoking, and you see people with the same cars, at the same mileage as yours, having no problems, then you'll notice.

So let your car warm up a bit in the morning. It's like you warming up before a good run.