I donīt think that the new M3 engine has more than 4.0 ltr., there are some reason:
1. because with 425hp that meens that the new engine has fewer than 100hp / ltr., that was lower than every M BMW from the past till now and also lower than the new Audi RS4...and BMW is much more experienced in the prodution of high-performence engines without turbo.
2. Mr.Richter from the BMW M-GmbH stated that 0.5 ltr. is the perfect displacement for every cylinder, that meens V8 = 4.0 or V10 = 5.0.
3. The new M3 - V8 engine was developed from the M5 - V10 engine with two cylinders cut off...that meens also that the new engine comes with 4.0 ltr.
I think the 4.4 ltr. thread comes originaly from the german car-newspaper "AutoBild" in which the journalist Georg Kacher stated in August 2005 that the new engine was an 4.4 ltr. with 425hp.
I beleave the new M3 engine becomes an 4.0 ltr. with horsepower in the range between 414 and 434.