Another key point was 1996, when the computer was upgraded from 8-bit to 16-bit. Better fuel management processing allowed the catalog specs to be changed from the original 255 horsepowers to 265 horsepowers. That was version 4. This was also when the rear tail lamps were changed from solid to 3 circles on each side.
Non-BBS 17-inch alloy wheels were introduced at this time. The RS-R would come with these new wheels painted in black. Since then, the RS came with these standard while the rest came with the original rounded 16-inch, which by the way, changed designs to a flatter 16-inch (starfish-like) for v5 (1999).
Do note that these version numbers are dependent on the serial number of the car. It can be found at the center top location of the firewall when you open the hood. For example 400000 ~ < 500000 would pertain to v4. The newest cars found in the US most probably came in the 300000 ~ range. But I'd still like to know if any 4s actually came in. By this time all 5 speeds came with twin oil coolers.
The only cars with the Dolphin wing and the original solid rear lamps were v3. Since then, some people went through the trouble of changing the rear lamps to the original solids or vice versa. Folks who reverted wanted the original look together with the Venturi spoiler while the latter wanted to make it look like the newer and more powerful renditions.
1997 (v4.1?) was when the original stylized infinity emblem was replaced with the Mazda emblem used today. This was also when the ugly-looking airbag steering wheels became standard equipment.
Besides the general issue dealing with cooling the engine room, quite a few folks with v1 and v2 had problems with the hard plastic-like block that had the main radiator cap. People used to just change the cap to one that would maintain a higher pressure. The problem was that it worked only temporarily. It was only a matter of time before the body holding the cap started to crack. That's serious stuff. By v3 the material was changed to a metallic block and the problem has since subsided.