Echo Automotive, the Arizona-based company offering add-on hybrid-electric kits for fleet vehicles, has been forced to shut down. According to an SEC filing on August 6 of this year, the company had defaulted on debts two days prior, and that “… at this time, the Company does not have adequate liquidity to repay any outstanding obligations.”

Echo had previously bought the intellectual properties of Bright Automotive during a similar situation back in 2013, but Echo avoided continuing on Bright’s development of a standalone, lightweight plug-in-hybrid van.

SEE ALSO: Echo Automotive Completes Acquisition of Bright Automotive Assets

Instead, it developed a simple plug-in-hybrid system that it said could save fleets between $30,000 to $45,000 in fuel expenses over a decade. The 9.4-kwh lithium-ion battery pack mounts in the spare tire well, and all the associated bits — like the transmission-mounted electric motor — were designed for easy installation and removal.

While the system wasn’t able to move vehicles under electric-power alone, the motor would help out the gasoline engine enough to offer what Echo said was up to a 50 percent savings in normal driving. Kits for both the Ford E-Series and General Motors’ 2500/3500 Express and Savana twins were either available or in development.

Green Car Reports