On diesel the later software update allowed lower speed passive regen’s around towns, as it started to happen the fuel economy dropped like a brick, if the regen failed due to turning the engine ff it would attempt it when the vehicle’s reached optimum conditions up to temp etc and yes the fuel dropped again. if it failed t regen after 3 attempts you woud see a waning or light and be advised take it up an open road under similar conditions seen in your Sportage handbook This would be done around every 300 miles.