The T1N is the pre 2007, and the NCV3 is the 2007 on up. Neither rides as good as the Chevy van, we've had both. The NCV3's do drive wonderful. They also are a physically larger vehicle.
You can expect 21+ mpg in the T1N, and 16 to 18 mpg in the V6 NCV3. The new 2014 4cyl, 7 speed combo seems to be equaling the T1N 5cyl in mpg, plus has more power.
The V6 takes 13 qts of a special 229.51 European spec 5w-40 synthetic oil. the 5cyl takes 9 qts I believe of 5w-30 or 40 regular diesel motor oil. Most folks use synthetic. The new 4cyl takes 9 qts of the same oil as the V6.
The filters for both, air & oil, on all 3 engines are the same price out there as any other normal vehicle available in the USA. Oil filter about $8-9.00, Air about $19-21.00, and cabin filter about $27-30.00. Oil filters, especially on the V6 and new 4cyl need to be Mann, Hengst or Mahle brand. The other common brands of oil filters seem to be a mish mash of Chinese or old eastern communist block country of manufacture that are not the best quality. Some have collapsed in use and caused all kinds of nasty terminal engine problems. Advice there, stick with Mann brand.
The turbo resonator folks have mentioned, is on the 2004-06 5cyl engine. Easy to replace with the metal aftermarket lifetime unit. Sticking with OEM replacement means carry a spare.
The 2007-08 V6 engine had a drivers side turbo to intercooler hose that was too short and needed to be replaced with a $100.+ longer hose from MB. That was up to the owner to find out about. No recall. It would come loose and you were dead in the water till reattached. No big deal to do it, just that it had to be done. Aftermarket fixes didn't always work either. 2009 on up has the longer hose that has been modified a couple times for even greater reliability on the newer ones.
Oh I forgot fuel filters. 2003 has one type, (and don't run out of fuel on a 2003, no in tank electric fuel pump, hell to get restarted). 2004-09 takes another type. 2010 to mid 2012 takes another, and mid 2012-14's take one that costs upwards of $100.00. The pre mid 2012 filters are around $32-38.00. 20k mile change intervals on fuel filters up to 2013. 30k after that.
Hope this helps....