From a fuel efficiency point of view the 1.4 is ample, but the additional torque and performance of a turbo motor would sweeten the deal that little bit more. (torquingcars.com)
«Best - ever efficiency points to clean, green gas - diesel engine.» (sciencedaily.com)
Engines are usually most efficient at 40 % of the load, so you are actually only a bit above the maximum efficiency point. (mechanics.stackexchange.com)