Is it a waste of time coasting & driving in as low a gear as possible to save fuel, since theres no difference?

YES. I think global warming is more important.

You want to be in as high of a gear as possible to save gas.

learning how to drive better and keeping car in best shape as always been smart coasting only a small part doesnt help much unlees you live on a mountain but learning to let off gas and slow down by coasting to a stop does save fuel driving in a lower gear doesnt that would burn more you know your going to stop at red light let off gas when light changes take off slower

Hate to play devils advocate here but there’s an enormous difference in fuel savings by keeping the crankshaft rotations as low as possible on flat ground.

If you see no difference with your car I’d head straight in to the fuel and ignition systems to find out why! Probably poor spray patterns on the fuel injector nozzles, bad ignition wires, sour secondary coil voltage or scabby spark plugs.

I think the best way to save fuel is to maintain your vehicle engine and fuel systems.

The heart of any vehicle is its engine and fuel system that powers the vehicle. Maintenance is essential to long engine life as well as the element to the promotion of energy efficiency. Planned maintenance to capture the most serious problems, like faulty oxygen sensor, and can save up to 40 percent on fuel costs.

You can maintain peak performance of your engine and fuel systems using high-quality additives for oil and gasoline. High quality products offer cleaning, packaging, lubrication and value above and beyond what is typical in engine oil and gasoline.