I am not familiar with the AH5, but I almost bought an AH7 before this and I would have if they offered me the deal they did after I took delivery of this. The 7 series hybrid was a freakin rocket ship. The hybrids generally produce more HP because of less stress on the engine from the AC motor and the like. The AH7 has 50 more HP than the base. They offer really good incentives like the eco credit and the hybrid models come with some goodies standard that you would have to special order (like alcantara head liner). As far as i know, they are only rear wheel drive.
The trunk space wasn't a huge issue in the 7, but I would see it be one in the five.
2012 535xi|Dark Graphite|Black Interior|M-Sport|
Prior BMW's: 1987 325e|1993 740i|1998 740il|2002 745li|2007 750li|2006 750li