I print my own cards and print cards for others, too. The paper I use is, of course, flat and does have a fold crease in it. I just did a small order for someone - 15 assorted cards and envelopes - and deliberately did not fold them. They are not only easier to ship that way, they are easier to store and the customer wants to use them over time, so that's a consideration. Folded, not folded - certainly would not be a deal breaker or maker for me. Less or more expensive shipping - could be.
And your cards look gorgeous, Gill. Not a car fan but it's unique and classy and I really love the other two scenes.