oh this is an easy one. The 4.8 is totally worth it. the post facelift and updates alone make it so, but the engine will be even more worth it.

how do u get it? easy. play the safety card! the new xdrive in the 2004 and newer is way better than the old version. add in all the other features (I believe they came standard with nearly every option) and she will be asking you to buy it.

Just don't race around with her in it before you buy. if she is educated she will point out that aggressive drivers have a high correlation with abusive men, and aggressive driving is only defined by the individual woman...

take her to it, show her all the safety stuff (do your homework first), let along yours is old and less safe. go for it!