The NPN design is also not a good choice because the Darlington within the DME only pulls down to about 0.5-0.7vdc when it turns on. This we felt could result in the NPN not activating (saturating) fully. With the PNP design the issue goes away because while the coil is not charging both the base and the emitter of the PNP are at 5vdc. Then when the DME darlington grounds the DME pin 1 it very quickly activates and fully saturates the PNP. It's very easy for the voltage at the base to drop 0.7vdc lower than the Emitter's 5vdc and the PNP activates very quickly. In summary: the DME pin #1 coil drive signal never gets to 0vdc it goes to about 0.5 to 0.7 depending on system voltage and that could be problematic.
As far as the turn off time of the PNP the scope trace shows no issue here, it turns off very quickly and cleanly. The only issue I'm working on now is cleaning up a slight negative spike on turn off. Here's the actual scope outputs from the input and output for the circuitry, taken while actually running in car. I'm not sure how much cleaner of an output signal I can get after I cleanup the negative spike where it dips about -2vdc on turn off.
And that output is always clamped at 5vdc when high.
And that PNP circuit is a basic design it does not have every component in it, several diodes are not shown and they have special purposes to help insure quick on and off times for the circuit. So please don't make the assumption that's the complete circuitry as other components are involved (ie: capacitors and diodes) for noise reduction, circuit stability and overcurrent protection if improperly wired.