We continue to transform our vehicle fleet by adopting low-carbon technologies such as hybrids and plug-ins, and biodiesel fuel in those vehicles that have diesel engines. We are acquiring commercially available hybrid and alternative fuel technology as vehicles are due for replacement. We also are investigating emerging vehicle technologies for compatibility with our fleet requirements, and plan to introduce them as they become commercially available.
In 2013, the PHI fleet considerably reduced the amount of vehicle idling time. Idling time was reduced on average by 1.6 hours per day, per construction vehicle, during a nine-month period. Reducing vehicle idling has not only decreased our fleet emissions but saved an estimated $303,000 in fuel costs from April to December 2013. Other methods used to reduce vehicle emissions involved driving at posted speed limits, avoiding rapid acceleration and ensuring that vehicles are properly serviced.
In 2013, there were 235 hybrid vehicles in service across PHI. This included 81 hybrid passenger cars, 127 hybrid SUVs and 27 hybrid bucket trucks. Included in this mix were 10 Chevrolet Volt plug-in hybrid electric cars. We added our first plug-in hybrid electric medium-duty truck in 2012. No additional vehicles were purchased in 2013.
PHI is also part of a group working with the Electric Power Research Institute on the Department of Energy's Plug-in Hybrid Electric Vehicle Medium Duty Fleet Demonstration program. This program is promoting the development and deployment of plug-in electric vehicle technology for commercial application and includes Odyne, Quantum and VIA Motors as electric technology partners.