TOYOTA make great engines.Here in Europe the most common diesel engines are the 1DZ , 1Z , 2Z.They are assembly this engines since the 5 series,with only some few upgrades.In my opinion,the best engines running in the market,with no doubt.
Regards.
R.Feitor
The 15Z, if I'm not mistaken, is Tier III. I don't think Toyota will be releasing their Tier IV until sometime in 2013.
toyota makes a great diesel engine, ive only worked on thr 1Z engine, change oil and filters will run for a very long time