How can I prolong a clipped flower intended as a gift?

I have a couple zinnias growing, and I want to give one to a friend who will be gone for some time. The thing is I can only give it to them at like 5-6-7am and they'll see it at maybe 3-4pm.

What can I do to best preserve the flower for them to find it in a good state over the duration of this time? It's likely going to be placed on their vehicle, so heat and sun will hurt it I assume.

I've seen that if you slice the ends of the flower a bit it helps it take in water, but I wonder if that's a lot of stress.

I'd like them to see the flower the way it was in my garden, but I'm thinking that might be a tall task.

Really would appreciate any insight on this.

Thank you, and sorry, I'm not quick to respond