I'm curious, why would the 40i lend itself to shorter trips any more than a 30d
There is very little value to a diesel on a short trip around town, it's exactly the wrong environment for it, plus don't forget the DPF etc.
The 530e has a 4 cylinder petrol engine otherwise would be perfect. I like the 545e but then you're back to the facelift cars with black wheels etc. But the small fuel tank seems like an issue too.
To be fair I use my 530d for short trips (though not as much as I did as we just use the Mini for runs into town and I don't commute etc now) but the future isn't going to be kind to diesel is it?