It's always difficult, I always try and make rational car buying choices. I rarely manage to do this in reality though...
I think that providing that you use 'man logic' all car purchases above a Fiesta are completely rational!
I'm also re-positioning our small car 'fleet' at the moment Mike and of course all cars are being chosen on a completely rational basis, apart from one slight aberration that has increased the fleet size by one - in mitigation it was bought for Head Office!