Since you are looking at a small footprint radio, the only thing NEW that can fit even close to a 520's footprint - is the Uniden 980.
But that's brand new...
Can you spare a moment and look around for a Realistic TRC-465, PC-122 or even a Cobra 146GTL - those are small DIN style (means can be installed in the dash - and even with the 146GTL - may need a shoehorn to find/fit into the dash (a different grommet/plate) - a good working oldie of a radio can surpass much of the newer radios today by "knob placement" and ease of access to all the needed BASIC controls.
The only reason I'm mentioning this is due to the nature of a small car - in knowing ownership of quite a few different ones - ranging from Sprint, Aspire, onto Scion X-series, they don't provide locations, or room, to mount much of anything these days.
I've had to mount my radios BEHIND the Overhead Dome light and use a crossmember on the headliner to mount and hold the Bracket. This poses several problems for those not used to seeing their radio via mirror image, but it actually frees up your field of vision forward as well as keeping your eyes closer to line of sight for less distraction - working with a mirror image of oneself let alone seeing the radio as a "ghost image" in the Rear view mirror, you get used to it. And for the basic essentials of knowing a simpler radio and operation of it makes it far more convenient let alone safe for operation in a small car where you may not always been seen and may need to avoid obstacles and keep your eyes on the road. Which is not always possible with todays in-dash crap they call entertainment
In fewer words - it's easier to find home plate with fewer knobs than to operate a menu-driven radio or a radio with backlighting that has far more knobs. It's in the sheer complexity, that you can lose your way and find yourself too distracted and now you hit something or got hit by something - and you'll have to explain that to the cops if you're able to...
The simpler the operational character you use for your vehicle, the more happier the miles down the road become. .