A police spokeswoman said a car had hit a power pole before crashing into the Golden Homes showroom at the intersection of Cameron Rd and Church St, near the Gate Pā shopping centre.
A male driver was seriously injured and taken to Tauranga Hospital, a police officer at the scene said.
A passerby said it was not the first time a car had crashed into the house, which had only recently been repaired from the last crash.
The general manager of Steel Frame Construction, which trades as Golden Homes, Saint Whatuira, said staff were a "bit shaken up" following the incident.
"They are a bit distraught ... They have gone home for the day and probably tomorrow too."
Whatuira said a car crashed into the same showroom at Easter, but this time the damage was worse.
"It came through the front door and hit one of the internal walls which backs onto the kitchen," he said. "Thankfully no-one was in the way when it happened."
He said the company's builders and tradies had already started to repair the building, but the showhome would be closed to the public until the home was fixed.