Authorities say the suspects used a rock to smash a window to get into the dealership.
One of the vehicles was involved in a hit-and-run crash in Wauwatosa, according to police. The driver reportedly lost control while trying to turn onto Mayfair Road and traveled a short distance on the wrong side of the road.
The driver eventually crashed into two poles and came to a stop near Menomonee River Parkway. Whoever was in the car fled before police arrived.
Fingerprints and DNA were collected from the car while it was in police custody.
"The message isn’t getting through," said Jim Tolkan, the president of the Auto Dealers Association of Mega Milwaukee.
He says in recent cases, the suspects have been juveniles with criminal records.
"Kids get arrested and they get released and they re-offend," he said.
He says most dealerships have already implemented extra security recommendations, like locking keys up overnight.
"Virtually now there are no customer cars being stolen," Tolkan said.
But these incidents continue. He says there have been six in the last month. He is now contacting state legislators for help.
"You have to try to do something legislatively that might help deter these activities," Tolkan said. "Harsher penalties maybe, minimal mandatory penalties, maybe minimum mandatory penalties even for juveniles."
Police say no one has been taken into custody and it's too early to say if the three incidents are related.