Might I suggest you still keep an eye out for the DA-40 TDI with the new (announced, not yet available) 2.0 engine or the DA-50.
Top performance for a normal 1.7 liters DA-40 TDI, according to the POH is 140.5 knots TAS at 6000 feet PA, on just 7.7 USG/hr (ISA, MTOW). This is 100% power, but the engine is rated for 100% continuous. This doesn't fill your requirements, but it's not that far off. And things can only get better...