The video for DM How-To #5 is actually from 4.7.5, I believe. With that one I simply had two radial force actors set to fire off a split-second apart to blow the pieces back like that. Nothing fancy, just enough damaging applied and enough force provided by the radial force actors to kick the pieces away. 
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Can you post your DM settings with the number of fractures used for the DM? I imagine it would be similar to the one displayed above though. I’ve not noticed this myself, but I don’t often test this with any vehicles either. I can see if I’m getting the same results in our Vehicle template and go from there. Typically any sluggishness or freeze that I’ve seen has been due to have too many fracture chunks and keeping chunks in the scene longer than needed. The APEX Destruction is all handled on the CPU to make it GPU agnostic instead of only working with Nvidia cards. This can cause laggy issues when using too many fractures or too many DMs that are all fractured. There is also a hard-coded cap of 2000 fracture chunks per scene at a time. Anything over that get destroyed immediately.
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This seems more to do with the setup of the vehicle. I’ve only really dealt with the Vehicle Template one that is available with UE4. Beyond that is another territory. I don’t mind looking into it though if you’ve got an example and how you’ve setup the vehicle. I’m sure you’re using a custom setup that isn’t as close to the setup of the basic Vehicle Template.