Opinions - wife wants to sell the 4.6

[racingbmwm3]

So my wife has given it over a year before deciding that she doesn't want to keep the 4.6. I think the big push was a podcast from Freakanomics about gas mileage...
And really, it is probably better for the car since she only drives about 6 miles per day, not really fair for the car to never get fully warmed up.

So, I've been putting together suspension parts for a big rebuild this spring, and if we chose to sell it private party, I think we could sell it for more money if I went ahead and replaced all the parts that I have now. But my garage isn't heated, so I don't really want to spend a weekend in sub 40 temps doing this.
Or we do a trade in for a new car and I try to make up the difference in price by selling the spare gear we have for it (Mediabridge, Sirius, style 87's/or winter wheels, 1/2 complete suspension rebuild kit with PF poly front bushings, factory roof rack, etc).

We both really love the car, but agree that we are doing it a disservice with the short commute.

I would like to make sure it goes to a good home, but I'm also feeling lazy and just want to make it a quick clean process...opinions please.