Indirect fire weapons (mortars and cluster bombs) have their range heavily reduced by high frame rate.
Flamethrowers do not work correctly at high frame rate, and barely leave the weapon area of the car 'sputtering'
Both of these are true even when limited to 60fps by vertical sync. To get the game to work as intended, we need to get framerates down to about 25-30fps, or find a way to modify those weapons specifically.
I've experimented with cpu limitation for the i76.exe process, and while there is some success in making these weapons work, it makes the whole game stutter.

I just blew up my own car because the mortars shoot directly in front of you, and damage YOU instead of the enemy. So I can confirm on my end it's a problem too.
How did this problem not get caught by GOG? Was this game even tested?
I really hope the community can find some kind of fix, because this is starting to feel like a waste of $5.99.
EDIT: I've dug up some info on various forums from a few years back about people imposing a heavier load on I76 to get the framerate down - things like enabling max AA and AF in the video card control panel. Didn't work for me.
The other thing to try is a CPU throttling program, but it seems you've already tried that.
http://vogons.zetafleet.com/viewtopic.php?t=149&postdays=0&postorder=asc&start=20&sid=eeca21cbd708a0d88e3ffbaaa2a1dd70
Here's the forum where I found some people talking about the same issues... the same issues that existed in 2007.

Aw, no more cheese 3-mortar mantas
LOL
- Bobby B

Psh, nothing's more cheese than a dover stag pickup with 4 Dr. Radars :P

Haha, well at least you can turn off your engine to avoid those :p
Anyone have any other suggestions for the framerate problem? This is the only thing that's stopping me from playing this game seriously at this point. Leaving the windows resolution menu open and using dgovoodoo leaves me with almost no problems. I can run the game at beautiful quality, except that Taurus is still all screwed up and mortars and flamethrowers are sort of useless. I've tried throttling but it ends up kind of weird.

Have had great success throttling with CPUGrabber under XP, but you must set the affinity of CPUGrabber to ONLY the cpu used by i76 - cpu0
You'd think it'd work set to both, but it doesn't. At about 70% on a 2.33Ghz Core 2 Duo I eliminated the dreaded wheel wobble, got taurus driving straight and fixed the mortars and flamethrowers.

Actually it makes perfect sense that the CPU Grabber only works with IE76 set to one CPU.
If it is absorbing two CPU's that means the CPU that your IE76 Exe is set to only gets half of the Grabbers "Sponge" applied, and that allows the CPU to give enough power to IE76 to mess up the frame rate of the game,which is the problem. JUst on half of a Duo Core is something like ten times the power of the CPU the game was designed to work with.