There have been 2 or 3 good postings about VDIM over the past few weeks. If you use the forum search tool you should be able to find them. There are links to some good web sites to explaining the tech involved.

Simply put however, TRAC and VSC are component systems of VDIM. The reason you don't see VDIM on non-hybrids (yet anyway) is that electrical steering is also a component of VDIM.

Two climate control systems, one inside and the other at the tailpipe.

2007 Camry Hybrid (in service June 2006)
FE: 6.77L/100km (34.8 mpg) over 37750km (23450mi)
75% city - Ave trip 20 min - 2 Winters