With the oldest WRX now dating from 2000, corrosion is a possibility. It is unusual to find a rusty one, so any rust may well indicate a crash repair or poor quality respray. Stone chips will be obvious on the bonnet and front bumper, but the roof can also be prone to damage from road debris.
As well as the usual body checks, look carefully at the doors and wings for dents and dings. The metal for these panels is quite thin and makes the WRX more susceptible than many other cars.
More than most cars, you also need to inspect all of the Impreza WRX's body kit very carefully. Does it match the model and age of the car or has an older model been updated with STI part? If extra or larger spoilers have been fitted, make sure the fixing holes have been properly rust-proofed. While checking the exterior, be sure all of the shut lines are even.
From January 2006 onwards, Subaru offered the Spec D option, with 'D' standing for discreet. This allowed owners to order an STI with a smaller rear spoiler and silver-painted 17-inch alloy wheels for a more under-the-radar appearance.
Perhaps the most distinguishing feature of the second generation Impreza is its headlight design. The early Bugeye models have large round headlights and many have been replaced with aftermarket conversions. Make sure they are solidly mounted and the headlight beam points where it should. Any garage should be able to check this for you. Even the facelifted Blobeye WRX has witnessed many owners change the headlights, usually with Morette items. The later Hawkeye models usually have their original headlights.
PHer's view:
"Frameless doors look cool but they can stir up a bit of wind noise, so not ideal if you have to commute in the car long distances."
John Newton