There are numerous commercially available neck and back support/cushion/pillow devices which are commonly attached to seats by vehicle owners. To our knowledge, there has been no published research on the biomechanical effects of these devices in low-speed rear impacts. To address this, a series of 54 simulated low-speed rear impact tests were conducted using a validated remote-controlled crash sled system. All tests utilized an instrumented BioRID II rear impact anthropomorphic test device (ATD) restrained using a 3-point seatbelt system in a 2018 Toyota Camry LE driver’s seat. Two delta-V ranges were used: a lower range from 7.2 to 8.0 kph (4.5 to 5.0 mph) and a higher range from 10.5 to 11.3 kph (6.5 to 7.0 mph). Six neck only devices, one combination neck and back device, and three back only devices were assessed. Two tests per delta-V range for each device and each device adjustment position were conducted and compared against five reference tests without any devices at each delta-V range. Statistical analyses and comparison of the biomechanical responses between each neck only and back only devices and the reference tests at each delta-V range were conducted. Additionally, Nkm, LNL, WIC, and NIC were calculated for each test. While not all devices and/or delta-V ranges showed consistent effects, the results indicated trends for certain peak biomechanical measures. Specifically, these support devices demonstrated a tendency to increase the tension forces in the upper neck, lower neck, and lumbar spine. Additionally, the back support devices tended to increase the head-to-head restraint contact forces as well as upper neck flexion (positive) moments. This study presents a parametric investigation into the biomechanical effects of various neck and back support/cushion/pillow devices during lower-speed rear impact exposures. The focus is on assessing changes in biomechanical measures associated with the use of these devices, and the injury criteria calculated should only be compared with the reference tests.