I know this is an Android centric forum, but an Android radio is the last thing you want. If that's what you are considering, you should know that those radios are made by fly by night companies with crap specification, low quality parts, and zero customer services.
Aftermarket radios primarily come in only a few sizes, then you install them with vehicle specific adapters and wiring harnesses. Check out Crutchfield as Hallux linked to, enter your vehicle info, and they will show you what radios will work out, plus what installation accessories you'll need. Be prepared for some sticker shock, too. The radios aren't too bad if you just want something basic, but the installation kits can be pricy due to all the system integration modern vehicles have. OEM radios have become the heart of many vehicles.