Well, assuming that drivetrain loss of 25% on an auto is a reasonably good guess, you then need to work 'backwards'. So, divide your RWHP figure by 0.75 (this is basically saying that the RWHP figure is 75% of the FW figure) to get the FWHP.
But in your case, the losses are less since you have a manual box. I've seen figures like 15% bandied about. So, 380/0.85 = 447. This is pretty close to the figure you quoted.
But in the end, RWHP is what really counts, and FWHP is what you talk about in the pub.
380 RWHP seems very strong for hybrids at 1.1 bar!!