NHTSA publishes a list of civil settlements here:
Fiat Chrysler was recently fined for inadequate protections on Jeep gas tanks, but I did not see that on the page linked above - so the list isn't entirely current.
NHTSA may not be the fastest regulatory group out there, but they have shown a willingness to go after car companies that do not issue timely fixes for dangerous problems. Automotive software bugs will eventually kill people. Unfortunately, NHTSA probably won't care until then.