Dismal sale numbers and a rising inventory which at the end of February, stood at 6,300 vehicles, enough to cover 154 days at the current rate it sells cars, are to blame for General Motors decision to stop production for both the Chevy Volt and its European cousin, the Opel Ampera, for five weeks until April 23.

“We need to maintain the right inventory levels and continue to meet demand,” GM spokesman Chris Lee told Automotive News.

On Thursday, General Motors told the 1,300 workers building the Volt at its Detroit-Hamtramck assembly plant in Michigan that the shutdown would take place on March 19.

Last year, GM sold 7,671 Volts, which was a far cry from the 10,000 units it hoped to deliver. This year, Volt sales dropped to a five-month low of 1,023 units in January but picked up to 1,626 deliveries in February. Still, that’s not even close to the 45,000 Volts GM aims to deliver in the States this year.