If your inverter fails, could it damage your car? If so, a fuse is a good safety feature. Select fuse current to match your inverter.
Anderson SB50 connectors are inexpensive and rated up to 50A. These would be a good choice for a quick-connect port. Buy two identical connectors. Wire one inside the car with 4 gauge stranded wire and a suitable fuse, Wire the other to your inverter. Use cable ties to hold the car connector in place so it doesn't vibrate when driving.
Here is one vendor, but many people sell these connectors:
http://www.newark.com/anderson-power-pr ... dp/96F6194
If you buy SB50 connectors, you must either buy the housing and pins separately or buy the kit with both housing and pins. Don't get fooled if you see housings for sale cheap without pins.
It's recommended to crimp the pins with a fancy tool, but you can also solder them. Just be careful to avoid getting solder on the contact end of the pin.