The problem lies in the fact that carmakers are refusing to certify the crash-worthiness of hybrid cars with partitions, which could potentially lead to a minefield of lawsuits if the partitions are found to be unsafe. According to automotive engineer C. Bruce Gambardella, putting a partition into a hybrid vehicle "changes the entire interior environment and takes us back about a half a century in automotive safety."
Additionally, Toyota and Honda have issued warnings against using their hybrid vehicles as taxis, claiming they weren't designed for "heavy commercial use." This is contrary to findings made by the New York City Taxi and Limousine Commission (TLC), which lists the Honda Civic Hybrid as an approved vehicle for taxicab use. The TLC also lists three Toyota vehicles in its list of approved vehicles.
Ford, meanwhile, has stated smaller vehicles, such as a hybrid or fuel-efficient econo-cars, put passengers at a higher risk of coming into contact with the partition, especially in cars that were not designed for taxicab use. Previously, many taxicabs used the stretched Ford Crown Victoria as a base, however the TLC's mandate requiring all new taxis to achieve at least 25mpg means the Crown Victoria is no longer eligible. It's not just typical small cars that have the safety issue, however, with even the Ford Escape hybrid SUV susceptible to the problems. A Ford spokesman told a September 10th meeting of the New York City Council that "there is an increased risk for belted occupants to contact the partition in a collision" for "any vehicle with a smaller occupant space than the stretch Crown Victoria" and explained that such safety concerns are "not unique to the Escape Hybrid"
Despite the lack of manufacturer backing for using hybrids as taxis, one Australian outfit has proven the long term durability of batteries in hybrids, racking up over 340,000mi (550,000km) on one particular Toyota Prius, and replicating similar results on other hybrids.