In 60's terms you could put regular or Hi-test in it. Leaded of course. Unleaded is supposedly hard on an engine not designed for it. There might be additives available to offset that.
That all depends on the engine you have and the rear gearing.
At best, you'll get 10-15 mpg. Don't get this kind of car if you want to save fuel, because it's a gas guzzler.
Regular unleaded
If your gas gauge is not working on your 2000 Impala you need to take it in to a repair shop. There could be a fuse that needs to be replaced to prevent you from running out of gas.
Rated at 20 city / 29 hwy.....
17 city 26 highway
there are no drain plugs on gas tanks, you will have to siphon the gas out or take the tank down to get the gas out.
The 2003 Chevrolet Impala is a gas-powered vehicle.
The 2005 Chevrolet Impala is a gas-powered vehicle.
The 2001 Chevrolet Impala is a gas-powered vehicle.
The 2014 Chevrolet Impala is a gas-powered vehicle.
The 2002 Chevrolet Impala is a gas-powered vehicle.