M2 weight vs M235i and 228i

I recently came across a few 228i weight data points that really intrigued me.

First, was from the GSR Autosport 228i track build out thread. Apparently GSR acquired a very base if not completely base 228i and it weighed in at an astonishing 3091 lbs with 1/2 a tank of fuel. That number is mind bogglingly low considering I've heard everyone throw around 3500lbs as the m235i number. Now granted that may be accurate for a semi-loaded or loaded m235i but I am planning for an M2 build that's very close to base, which has me wondering what a fairly base m235i would actually weigh in at. I haven't found a weigh-in thread for one yet. This also has me wondering, what is the weight difference between the 228i and m235i engines? Is it really close to ~250lbs? That can't be right. There may be some additional engine cooling componentry and some additional oil and coolant capacity for the bigger engine, I just can't imagine the weight difference being quite that high.

Then here is another thread where a 228i weighed in at 3260 lbs with a few options. Still a very light car.

Bottom line, I think a base M2 may actually be lighter than we've been estimating.