Diesel Particulate Filter (DPF) has become a key technology in modern diesel vehicles to achieve low emissions, and the performance of DPFs has been improved through considerable efforts by manufacturers. While DPF is essential to meeting the stringent regulations for particulate matter (PM), it has a negative impact on fuel efficiency (FE) due to its periodical regeneration for burning off the accumulated PM in DPF. Hence, detailed assessments on the FE impact of DPF regeneration technologies are necessary to better understand the FE potential of diesel vehicles. However, few quantitative FE studies have been reported regarding the DPF regeneration technologies applied to vehicles introduced into the market.We investigated the influence of the DPF regeneration on FE performance using three new diesel vehicles with different DPF regeneration technologies. The tests were carried out as consecutive runs of a chassis dynamometer test cycle, covering the DPF regeneration interval and duration. Various driving conditions were examined as repeated test cycles of the JC08 and JE05 driving schedules of the Tokyo Metropolitan Government No. 2, or the US EPA Highway Fuel Economy mode. A multiple gas-sampling bag system was introduced to enable FE measurements without interruption during the entire operation of the repeated test cycles. The new bag system was important in the quantitative analysis of the DPF regeneration effect on the FE of the diesel vehicles.