Welcome to GasSavers,
The pistons inside your engine need to be moving for your engine to be running. Your car's computer knows this and keeps an eye on 'em, knowing what they're up to at all times. When you're sitting at a red light your computer provides small amounts of gas just to keep the engine from stalling, that's referred to as idling. Once you're underway your foot takes over until you remove it from the accelerator pedal, now you're coasting. The momentum of your vehicle is keeping your engine running, no gas is necessary 'til you drop to quite a low speed. This is Deceleration Fuel Cut-Off or DFCO. Your vehicle's decelerating, no fuel is being used. Just before your speed drops so low that your engine stalls your computer sends some gas in to keep things moving. There are different strategies for maximizing this "no gas being used even though the engine's still running" benefit. Each is unique to the vehicle in question. Some may be detrimental, you'll want to procede with caution. For that reason I'll hand it over (with any luck) to somebody with personal knowledge of your Yaris.
[QUOTE=Project84;147125I'm not "rich" by any means but I do have one advantage if you will... I'm a maintenance man.[/QUOTE]