HCCI is ideal for a series hybrid.

The big question is who's going to be first to bring out a series hybrid? Toyota? Honda?

My bet is for an outsider - Mitsubishi. They've already committed to going down the full EV route with in-wheel motors etc. For the increased range and quick refill capability that many will demand, they're going to want to put in a small, clean, low emission engine in the back somewhere. HCCI would be ideal for this kind of onboard generator set up.... no need to worry about idle or torque or lag or throttle response, just outright thermal efficiency.

http://mysite.wanadoo-members.co.uk/ecotech/ecot.htm