Hey Pioneer, you can get by with a 10 gauge wire if the run is short, like maybe mounting that inverter under the hood next to the battery. If you're going more than a few feet use 8 gauge instead. If you're going to mount the inverter someplace else in the vehicle, like in the cab or the trunk, and you're grounding the negative of the inverter to the chassis, make sure it is the chassis, not some thin metal fairing with a small screw. Electron movement through light metal will cause that area to corrode faster, so either run another wire back to the negative, or find a good place on the frame to ground the inverter negative.
We have one in our truck, it's a 750 watt, and I used 4 gauge wires already made up with large grommets on the ends and soldered joints from a golf cart repair place. I was concerned about the battery running down, so we installed two golf cart batteries, 6 volts each for 12 volts in series. Then when I drive, there is a switch on the dash that closes a driving light relay under the hood connecting the positive of the regular battery to the positive of the golf cart pair so they all charge from the alternator. After shutting the motor off, I just turn off the switch, the batteries seperate, and I can run my inverter or 12 volt appliances from the extra batteries all I want. The regular battery stays charged to start the truck back up. My 750 watt vector inverter can run our electric weed whip or any of my drills, it's real handy out in the field. You can even run lights in your house during a power outage from your truck that way, or use power for camping. Good luck, Rudydoo