sentences:  For reasons such as this the Working Group On Off Cycle Emissions is studying whether an extension of the NTE zone is rational as they ponder if there are spots on the engine map (outside of the NTE zone) that have a significant contribution in real life emissions.Their preliminary findings echo those of WVU as they found that the time of engine operation in the NTE zone is rather low.According to the US EPA there are technical limitations of NTE under limited operating conditions which have caused the EPA to "carve-out" (see graphs above) certain portions of the NTE zone to allow for these deficiencies.