Tractor supply had a 2000w gas gen on sale for $100. Get that.
Running a vehicle isn't worth it...the fuel use with the idle rigged to run at a higher rpm would not be good. I believe the old estimate for stuck in traffic idling is 1/2 gallon an hour.
The cables, alternator, batt may be able to source high current, but pulling 50-60 amps at a 100% duty cycle is "probably" not a good idea.
In an emergency for a few hours, fine.