The flat front sure isn't helping. But:
* Speeds are low anyway, thus aerodynamics are less of an issue.
* Undercar airflow would hamper things worse, with all that equipment hanging under there.
* Intercar gaps are an issue too.
* Weight is more of an issue w.r.t. energy use.
* A more aerodynamic car could be designed, but would likely cost more plus more to maintain, plus not have whatever advantage the LIRR and MN get out of married pairs.
* A train's long and slender anyway, thus theroetically should be well off (Though yes I've read that long freights with large numbers of open doors on boxcars and such are infact a source of drag).
* I'm not aware of any wind tunnel testing of rail equipment in the US, and even overseas, it's mostly for high speed services and turned towards noise reduction.
The gains in a reduced Cd wouldn't be much, and not useful at lower speeds, likely. And yes, the HHP-8s are supposedly more aerodynamic, but I think it's more a styling decision than anything real - note that there's always the opposite end of the locomotive in back and the Amfleet behind it.
It shouldn't be too hard to make up a model of an M-7, etc and ind tunnel test them, though...
