Why?
Something like the 'Dart' (for an example purpose only) has been in pre-production (R&D) for anywhere from 5 - 10yrs.
Hardly a "first year" unit, although it is in it's "first year" for the public to purchase.
You guys don't realize that all vehicles are "first year" models. Several make changes mid-year. (not as common as it was in the past).
Just because the exterior may (or may not) have subtle changes, there are numerous changes with every model year that are not plain to see by eyeballing / test driving the unit. (hardware, wiring, etc etc change EVERY year).
For every inferior issue they try to resolve, they create 2 more (as model years carry on), so in reality, a 1st yr run unit may be much better than the 4th yr run unit. YMMV.
Same mind set as when you hear someone say: "I'll never buy a car that was built on a Monday". Guess what? Every car on the road was built on a Monday (and Tuesday, Wednesday, Thursday, and Friday). Every unit spends anywhere from about 8 to 15 business days from start to finish on the assembly line.
There's no such thing as a vehicle being built in a day. Not in North America anyway.
IOW's - there is nothing more to fear by purchasing a 1st yr run vehicle, than a 2nd, 3rd or 4th yr run.
This site can be useful, as it is kept going by people like us - not an agency, or govt:
http://www.carcomplaints.com/