Simplify the following text for a Grade 6 native English-speaking person.
Original: Consequently , the Sintra 's popularity plummeted even further , forcing Opel and Vauxhall to drop the model in 1999 .
Simplified: The reason for the Sintra to end production was because EuroNCAP tested a 1998 model and found it only scored 2.5 Stars , forcing Opel to drop the model in 1999 .