I have a 95 318ti BMW, four cylinder, and I am in the process of remodeling and would like to upgrade my engine as well. Is there any possible way I could find a six cylinder engine to replace the one I have now and if so, would it be worth all the hassel? You should be able to replace it with a BMW 320i engine. They are the same model car but you might have to find different motor mounts.
The New BMW Efficient Dynamics Engine Family
RT 2012 BMW Z4 sDrive28i new 4-cylinder engine: 2012 BMW Z4 sDrive28i at the 2011 New York Auto… 
2012 BMW Z4 sDrive28i new 4-cylinder engine: 2012 BMW Z4 sDrive28i at the 2011 New York Auto… 
@ Benz is trying to copy the new BMW 4 cylinder how cute! To bad they missed the BMW logo on the engine
Porsche Panamera V-6 vs. BMW 640i... if you are dying to pay $75,000 for a car with a six-cylinder engine, you now have a choice! 
BMW Denies Report Of 12-Cylinder Engine Deal With Mercedes-Benz 
BMW Headquarters (BMW-Vierzylinder) is the "BMW four-cylinder" building at the BMW Welt/Museum/Factory site in Munich. Designed by Austrian architect Karl Schwanzer, it resembles the cylinders and links of a BMW car.
The BMW Welt, Museum and Factory site in Munich. The obvious attraction is the ultimate driving machines that are displayed and built here. But, the building architecture is just as BMW-like, and takes inspiration from the car.
Seen it done a few times and figured id give it a shot. I Didnt put much effort in so im not expecting a perfect result however it came out rather well IMO.
I wish i could be revealing something a little more than a 2.5L l6 (would much rather have a 3.2L l6) but it will do...