Hi noobie here, kinda...

I am considering buying a 2003 350Z with 51K miles. The car has some minor
underbody scrapes on the paint, it is pearl white. I am driving it until
Monday to see what I decide. I have some questions if you guys could help.
TIA.

1.) Can regular or mid-grade unleaded be run intermittently instead of
premuim gas all the time?

2.) Is $16K from a dealership a good price, if I get a warranty?

3.) How reliable is this car? What about cost of ownership, ex: tune-ups,
maintenence, etc..

4.) What is real world gas mileage (assuming I drive responsibly)?