They do like some stick every now and again

4 miles each way won't get it warm so the EGRs won't be working. They don't start to work until the engine is up to temp. Whilst they do cycle when the engine is started, I bet there's a bit of crud that only gets loosened when you give it some welly.

Buy her an electric car (or bike) for work and use the Sport properly at weekends.  2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed