There currently isn't any entry level diesel subcompacts available. The Getz is phased out already and the Accent's CRDi engine isn't here yet. The only way to get a diesel subcompact right now is to dig into the 2nd hand car market.
If you're willing to go to the pre owned market, the only choices available are the Getz and the Accent. Focus Hatchback is ok pero baka malaki for your needs.