In a memo to U.S. retailers obtained by Automotive News, McLaren said deliveries of its plug-in hybrid, the Artura, are delayed on average about four months as the British automaker institutes “enhanced testing procedures” to improve quality.

McLaren said the measures provide “additional checks and testing in our quality control procedure.”

Spokesman Roger Ormisher confirmed the delay.

“To implement these quality control procedures, we have temporarily slowed production,” he said.

A McLaren retailer said customers planning to take delivery in May can now expect to do so in September.

It’s the latest setback for the Artura, originally scheduled to arrive in fall 2020.

Buggy software and supply chain delays pushed the sales start to late last year. Shortly after, faulty nuts on high-pressure fuel pipes triggered a recall.

The latest hiccup is frustrating some retailers. One said multiple customers had canceled orders, put off by Artura’s rocky launch.

The Artura is a critical model in McLaren’s pivot toward an all-electrified lineup by 2026. Challenges are partly related to the new model’s complexity.

It is the first model on the company’s lightweight carbon architecture, the first to feature a V-6 engine and the first to offer a suite of advanced driver-assistance technologies.

At a dealer meeting in April, McLaren’s new CEO Michael Leiters said improving product quality and resale value is a priority for the brand.

“It’s about quality, quality, quality,” a source said of the company’s message. “Making sure the cars are perfect before they leave the factory.”