On average I cover around 1100 miles per month.
With my ED30 it used to cost me around £250 per month.
I then moved to the dark side and now spend around £120 per month, covering the same miles.
Drive isn't the same, but I'm happier knowing how much I'm saving, not just with the fuel, but with the tax, insurance, and so on.
One day I'll buy a M3 as a weekend car though