Rockstar have released some more details and a couple of low-res screenshots from the Grand Theft Auto V Special and Collector editions.
 

The high-end Khamelion electric car. Available in Grand Theft Auto Online as part of the Collector's Edition.

 
Additional Weapons
Regardless of which version you've chosen, your local Ammu-Nation will always be stocked with a pair of special firearms at no additional cost that also have their own unique customization options, skins and attachments - the .50 Caliber Pistol and the Bullpup Shotgun. You'll also have access to the Hammer, which acts as a brutal melee weapon.
 
Bonus Outfits, Tattoos and More
When visiting any shops around Los Santos and Blaine County, Michael, Franklin and Trevor will receive a special 20% discount along with access to special items either in their personal wardrobes or from stores. Each character will receive 1 outfit each, one additional article of clothing (shirt, hoodie and jacket) each and a tattoo.

Michael, Franklin and Trevor each sporting some of the unique additions to their personal wardrobes.

Custom Characters for Grand Theft Auto Online (Collector's Edition only)
GTA Online introduces a new spin on traditional character creation with the hereditary-based creation system. Select your character’s appearance by choosing your parent’s heritage, then use the gene dominance meter to dial-in which parent your appearance favors more. Additionally, you'll customize your character's daily activities - everything from family time to illegal work and sports to couch potato hours all have an impact on your character’s appearance and skill set (and you can always rank up your skill stats more via gameplay). As part of the Collector’s Edition package, you'll get Niko Bellic, along with both Claude and Misty from Grand Theft Auto III to use as parent options within the character creation system.
 
Special Ability Boost
Michael, Franklin and Trevor each have a their own unique Special Ability, which can be activated once each of them fills up the Special Ability bar based on various actions. Michael is an expert marksman - his Special Ability slows down time in a gunfight allowing him to pick off his targets with greater ease. Franklin is a skilled driver with sharp reflexes - his Special Ability lets him slow down time while driving any road-based vehicle, allowing him to quickly navigate through traffic with ease and take corners at high speeds. Trevor is a drug-addled sociopath with a short fuse - his Special Ability sends him into a rage, causing double damage to enemies while only taking half as much damage himself when hit. With the boost that's included in both the Special and Collector's Editions, the Special Ability bar will generate 25% faster.
 
Stunt Plane Trials
Take in Los Santos and Blaine County at breakneck speeds in the Grand Theft Auto V Stunt Plane Trials. In five thrilling and unique challenges, you’ll zip through mountains, deserts, oceans, and cities as you navigate through a maze of checkpoints, each placed to push your Stunt Plane to the limit. Completing each Trial will improve the piloting skill of your character. Compare your times with friends and vie for the top spot on the leaderboard.

Hit the streets of Los Santos with the CarbonRS sports bike.

Unique Vehicles and Garage Property (Collector's Edition only)
The Collector's Edition also features an exclusive garage to store custom vehicles, that comes stocked with the CarbonRS sports bike and the Hotknife - an open frame 1930’s style hotrod. In Grand Theft Auto Online your garage and the high-end Khamelion electric car, which is specific to GTA Online, are both purchased through in-game websites accessed through your Online character’s cell phone.