The most expensive problems are those that customers or interested third parties discover. If companies try to sweep them "under the rug," or invest resources to deliberately deceive the public, there is likely to be a big explosion as the pressure builds under that rug. This is what has happened to VW.
VW, a top-selling automaker known for its German engineering, clean-diesel technology and strong market share since 1937, cheated emissions testing using software in 11 million vehicles with small diesel engines worldwide. By recognizing when the vehicles were undergoing emissions testing, performance was modified by the software.