[tjts1]

The over run fuel cut off is different on every car. On our OBD2 volvo manual it will only shut off the injectors if you take your foot off the gas above 2000rpm with the engine warmed up and keep them turned off down to about 1300rpm. There is also a 2 second delay built in. If you're at the top of the hill below 2000rpm, the engine will keep the injectors turned ON. With the injectors off the FE gauge pegs at 99mpg while still going down hill at 20-30mph. With the injectors ON and engine in gear the FE gauge shows 50-60mpg on over run. With the engine idling in neutral the FE gauge pegs at 99mpg. The OEMs tune overrun to minimize emissions on the government's standardized test. Shutting off the injectors on over run affects the temperature and therefore efficiency of the catalytic converter immediately after the over run event. Some times its cleaner to keep the injectors running.
On my mercedes running megasquirt I set it up so it shuts off the injectors below 22kpa at all coolant temps (even right after a cold start), all RPM down to 1000 and there is no delay or taper. I also setup the idle air control valve to maximize engine braking on overrun. Its much stronger than any stock EFI car. In normal driving I get at least 50% of my braking done with the engine and this is with an automatic transmission.