G 400cdi or G 320 cdi

I am looking for a new G (my 350td sold after 12 years) the question is 400 td or the new 320 td, the 320 has to be bought again, quite expensive, the 400 can be bought as a year’s car. how is the machine, very vulnerable? how high is the consumption in G ? the 320 should consume? about.10. that would be sensational. for information I would be grateful! mercedesgray