I'm not sure but I believe that's it possible to get the required servicing done on a new car done outside the dealership and still meet warranty requirements - is this correct?

I ask because I've dealt with my local garage for years and would prefer to give them my business rather than do a three hour return trip to the nearest dealership  and then pay significantly more than what my garage would charge.  

Any drawbacks of not going to a dealership for servicing?  Would my garage have to use genuine manufacturer's parts (i.e. oil/air filters etc) or would aftermarket parts be OK? Someone told me that any vehicle software updates would not be able to bo done outside the dealership - guess that might be true.

Any comments or tips appreciated,  especially by those that don't use a dealership for servicing.