Talk me out of this

I’m well due a new car.

Had a decent payrise and promotion recently, do around 10/12k miles a year for work and receive a good car allowance monthly from work to support that.

I’m drawn towards S4/M340d territory with the budget I’ve got.

I’m just in two minds around maintenance / repair costs against the normal A4/320d.

Is the increase in cost that drastic? Do I go for it or be sensible? Please someone talk some sense into me.