This might be where I saw it, but I have a feeling that it was somewhere else too. In the edmunds.com "2007 Hybrid Sedan Comparison Test" dated 2007-07-22:
http://www.edmunds.com/apps/vdpconta...5/pageNumber=1
the last paragraph contains the statement:
"Details like an Atkinson-cycle gasoline engine (a distinction that helps the Camry nip the Altima in fuel economy) and packaging designed to accommodate the hybrid batteries with minimal intrusion into the interior speak volumes for Toyota's commitment to hybrids."
I interpret this to mean that the Altima Hybrid does not have an Atkinson-cycle ICE.

Stan