The 1.6 DCI 130 without any shadow of a doubt because when it was originally launched about two years ago it represented the cutting edge of diesel engine technology. It is chain cam.

Its exhaust manifold is inside the cylinder head so the turbo and DPF can be close coupled to the block. It has coolant heat retention circuits to ensure faster warm up at the parts of the engine that need it most. It has special plumbing for more efficient EGR. In the real world it is more economical than the 1.5DCI. And I have yet to hear of any trouble with it.