[john70t]

"Excuse me for a second"
Pull out phone. Camera/video. Pretend to push other buttons.
Place at head perpendicular.
"Yeah Bob, this is Frank. I'm running late. I'll have to call you in a few."

A team? Pushy? Don't take no for an answer? With $80k cash they want to throw at your car?
Stay in awareness mode. You never know. Keep distance. Look for possible weapons, escape routes and defensible positions. Leave yourself options for an out.

Be assertive. Ask them if they are from around the area.
How did they happen to notice your car?
Do they have a card (DNA/fingerprints)? You will call them if interested.
Have a nice day. Time for them to leave now. It's your place and your car.