This is wild... and for a used car. If it was a brand new car I would understand offering you a drive in a similar model. The whole idea of test driving a used car is to see if anything is wrong with that exact car you are buying.
And these days it is not impossible to find a 500K comment or repair with less than 5000km on it... or 1043km

. There is also an M2 driving around with a 400K+ comment (well I would hope it was commented) that was crashed during PDI and a very low mileage M8 with a R1M+ comment. Point being you cannot take anything at face value when buying used. You have to absolutely test drive the specific car you are buying.
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Whatever bean counter or consultant dreamed up this process needs to be fired because it is so far detached from a 'good' or even 'decent' customer experience.
I feel like the solution is:
Go to Porsche
Drive Macan
Drive Cayenne
Choose one
Negotiate extension on plan to be included in price
Acquire
Don't look back