Best Diesel Car under 15k

Hi All,

Looking to get out of my 1L petrol Hatchback and into a Diesel mile buster.

Budget is 15k max and it must be cheap to tax and insurance.

Currently averaging about 600km a week on the road all motorway driving so looking for a nice comfortable car with good MPG.

Dont really care about performance, really looking to keep service and tax cost as low as possible. I’m 28 clean license and no claims, currently pay a little over 500 for insurance and want to try keep that below a thousand aswell.

Please let me know your recommendations, I’ve had a look at Passats but didn’t really like them that much.