Replacing the battery in your Q5 involves removing the terminals. When you reconnect the terminals, your radio presets are likely to be cleared out. In some Q5s, you may need to re-enter a security code to get your radio to work again. Check for this code in your owners manual - it will usually be either a sticker or small card in the booklet. If you can't find it, call Audi and they will give you the code for free. In many Audis, the transmission "learns" how you drive over time and makes adjustments, so you may experience altered driving dynamics as your car re-learns your driving style after changing the battery.