As someone into vintage restoration its insane to me that historically having an undercoating on body and frame was considered a luxury feature that companies l

As someone into vintage restoration its insane to me that historically having an undercoating on body and frame was considered a luxury feature that companies like Porsche did. US big 3 were like who drives a car more than 10 years anyway? So half our cars are rusted out and unsalvageable even though the engine is fine.