"The U.S. National Highway Transportation Department said the rules will cost the auto industry about $39 million annually because automakers will need to add an external waterproof speaker to comply."
A $3 speaker and $1 of wiring per car will add up to $39 million? Too bad. Raise the cost of the car by $5 and stop whining.
No one puts off buying a car because it costs $32,535 instead of $32,530.
If you assume they manufacture ~500k new hybrids per year, then their quote works out to $78 per hybrid. To me, I wouldn't be put off buying a car if it was $32,608 instead of $32,530.
As for the speaker, if it's in the engine compartment it's probably rated for temperatures from -40 through 150F, if not more. Plus it's likely going to be exposed to a LOT of dirt/dust/water, while still needing to be heard. It also needs to probably make some non-trivial sound that is based on speed and shuts on/off appropriately. Maybe not $78, but definitely a lot more than $3 in my opinion.