How to model a car (year, make, model, trim)?
The first model is more accurate for your business needs. I would go a little bit further and include an index (unique) that includes NAME and YEAR.
If you keep the model as it is; for example, the model doesn't prevent you to have this data:

TRIM:
id     model_id     name     year
==================================
1      1            SL       2013
2      1            SL       2013
3      1            SL       2013


To avoid this situation create one index in TRIM with this:

CREATE UNIQUE INDEX trim_idx ON trim (model_id ASC,name ASC,year ASC);


And do a similar action for MODEL

CREATE UNIQUE INDEX model_idx ON model (make_id ASC,name ASC);