Heres a list of specs I found on a site. It doesn not say MP3's but the original owner said he played MP3's on it. Im sure you can fit a ton of songs on a DVD in standard format.
General
Product Type: DVD player with LCD monitor
Intended for: Vehicle
Width: 17.8 cm
Depth: 16.5 cm
Height: 5 cm
Weight: 2 kg
Dimensions & Weight Details: LCD monitor : 16.9 cm x 1.6 cm x 12.5 cm - 2 kg
Localisation: English
System
Form Factor: In-dash
Enclosure Type: Full-DIN
System Control Bus: IP-Bus
Supported Devices: CD changer
Parental Lock: Yes
Digital Audio Format: Dolby Digital output, DTS digital output
Security Features: Detachable faceplate
Features: On-screen menu
Monitor
Type: LCD monitor - in-dash unit integrated - motorised
Technology: TFT active matrix
Diagonal Size: 7"
Total Pixels: 336,960
Image Aspect Ratio: 16:9
Resolution: 1440 x 234
Widescreen Modes: Full, Zoom, Normal, Just, Cinema
Features: Anti-reflective coating, control keys, automatic dimmer
Manufacturer's product description
Are you ready for Car Theater? With a Pioneer system head unit or controller, you'll control a DIN-sized motorized DVD/CD player and 7" LCD color display. A component video output for the rear is supplied. And with the optical/digital output to a Pioneer master unit, you'll get theater-like Dolby Digital/DTS sound. Unless you start charging admission, you're going to be very popular.
DVD
Type: DVD player - in-dash unit integrated
Media Load Type: Slot-load
Media Type: CD-R, CD-RW, DVD, CD, Video CD
Audio D/A Convertor: 24bit / 96kHz
Dynamic Range: 96 dB
Signal-To-Noise Ratio: 97 dB
Response Bandwidth: 5 - 44000 Hz
Total Harmonic Distortion: 0.008%
DVD Repeat Modes: All, title, chapter
Multi-Camera Angle Select: Yes
Multi-Language Select: Yes
Remote Control
Type: Remote control
Technology: Infrared
Features: Joystick
Miscellaneous
Included Accessories: Cable kit, speaker
Cables Included:
Video cable - 3 m
Video cable - 6 m