Driving a perennial like you would drive a cheetah, landing to water without finishing in the hospital and losing your armor, weapons and money... the game would be much funnier it was all possible.
Well it is but only if you download this mod.
I took the characteristics of all the sports cars (Banshee, cheetah, comet, infernus, sabre turbo and stinger) and gave it to the other vehicles that are also still unsinkable.
All the boats behave like the speeder.
The bikes still have their default handling but can't sink any longer like the helicopters.
Don't hesistate to check out my other mods:
GTA III:
Fast unsinking Liberty cars http://www.gtagarage.com/mods/show.php?id=13194
Spring weather http://www.gtagarage.com/mods/show.php?id=13196
The invincible gangster killer http://www.gtagarage.com/mods/show.php?id=15777
GTA San Andreas:
Speed Andreas http://www.gtagarage.com/mods/show.php?id=13192