Speedometer is great improvement of gameplay in games where vehicles can be driven. No speedometer was implemented by Rockstar Games, though.
This speedometer is inspired by SpeedoIV and it's compatible with its textures and skin packs.
Furthermore as opposed to competitive speedometers made for GTA SA this one provides a way for total customization with .ini file as well as repleacable textures.
Also, three facts can't be forgotten as written below:

Fully compatible with GTA San Andreas v1.0 [US] HOODLUM No-CD Fixed EXE & GTA: San Andreas v1.01 [EURO] No-CD/Fixed EXE
Fully compatible with any screen (4:3, 16:9, 16:10...)
Open-source work, can be studied and modified by other developers.