I have imported a car (petrol) from Germany last year myself.
It's not a big deal, what is important check with dealer if they will refund a VAT back on export.
in DE:
- you need to get export plates (valid for a month, the 'red' ones - dealer that sold me my car helped with this)
- you need to get export declaration / documents from German customs when you buy a car (my dealer helped with this as well)
- when you cross border you need get to German side and they will scan / confirm export declaration (this is needed for German VAT return)
in CH:
- on the border you either need to pay VAT + Customs duty + 4% tax OR get a document (can't remember the number exactly) stating you will do that within a couple of days later
- if you get above extension document (as I did as I was crossing the border after 22:00) you need to get to some 'Zoll' place (I used in Embrach - it's close to ZH - there I didn't have to do any online application, nor use agency, just went to customs and within 10-15 minutes they did it all and I paid what I owed (VAT+4% tax) - they gave me a paper needed for MFK
- you setup an MFK (online)
- If you have no plates you need to organize insurance (as you'd have to do anyway)
- you do MFK and if it pases you go directly there and then to get Swiss plates, mount them on a car and your job is done
Overall, process isn't hard, German part was harder but that I got done with dealer from DE, Swiss side really goes down to 2-3 steps, get paper from the border, pay VAT / customs, do MFK
Also, Dealer from DE saw directly in system (or rather a customs agent they used) that car was exported (after German customs scanned export declaration) and refunded German VAT within 2-3 days.