Does the autostart really save gas?
Yes , but the amount will be different for everyone .
As usual, the answer is, “it depends.” Auto stop/start obviously won’t save gas in highway driving where you’re not stopping and starting but if you do a lot of city stop-and-go driving then yes. That said, owners of vehicles with that feature often find it to be a pain. I have no idea how well it’s implemented on a Land Rover. Plus, there’s extra wear-and-tear on the starter and extra strain on the battery. I’ve read the explanation of why that’s not an issue with modern vehicles but frankly I’m not convinced.