Installation:

1) add or replace the DFF files from the download into GTA3.img

2) Use a Collision editor and add / replace the .col with the one from the download

3) Open data/carcols.dat and replace the color line of the vehicle you want with this

(insert vehicle name) 95,1, 57,1, 49,1, 36,1, 20,1, 53,1, 1,1, 14,1


4) Open data/handling.cfg and replace the line of code of the vehicle you want with this
(insert vehicle name) 1200.0 2.0 4.5 1.4 0.0 0.2 0.0 75 0.95 0.80 0.55 5 200.0 24.0 R P 10.0 0.53 0 30.0 2.2 0.13 0.2 0.65 35000 0.27 -0.11 0.5 8002 0 1

5) Edit Default.ide and change one your prefered vehicle's line of code, for example:

100, 	manana, 	manana, 	car, 	MANANA, 	MANANA, 		poorfamily,	10, 7,	0,	163, 0.7

||

Followning the steps accordingly the car should run in the game just fine.