Not sure who your insurance is through or what your specific policy states, so I am just speaking from my personal experience and research:
NADA and KBB don't play a huge factor, but they are part of the equation (most of these sites low-ball). A total loss is valued by factoring in the price that reasonably similarly-equipped cars are selling for in your geographic area. And by that I don't mean list price -- they are looking at the actual selling price. My advice is to scour Autotrader (& similar) for other cars that are as close in mileage and options to yours as possible. You have low miles and are 6MT, so you may need to broaden your search outside your area. Depending on how recently you purchased your car, you can use the selling price you paid for your own car as part of your research as well.
There are also independent appraisers who will help you come up with a fair value for your vehicle. Talk to a reputable body shop in your area -- chances are they know of one or two who you could work with.
Try to go into this with 2 numbers in your head -- your ideal settlement price, and the minimum you'd be willing to accept. Work with your insurance company (with the help of the independent appraiser and an attorney if you happen to know one who'd be willing to help) to get somewhere in between those 2 numbers.
To address your last question, $27k is not unrealistic or unreasonable at all. Is that the ideal price that you'd like for your car? I think you may be able to push for more.
My car was damaged this Summer and for a few weeks there I thought it may be totaled so I did a ton of research. I was shopping for an E92 that was equipped similarly to yours, and most of the ones I saw were CPO selling in the low $30k range ($31-32-ish) with a few stragglers with accident histories selling around $25-26k (all '08-09 6MT E92s with <45k miles).
2008 E90 335i // Black Everything // photos
COBB tuned / QTP e-cutouts / Helix FMIC / cp-e DCI / AWE BOVs / Black M6 wheels + Toyo Proxes
(and yes, I am a girl)
Last edited by cmyk; 12-22-2012 at 12:13 PM.