The Annis ZR350 from the Los Santos Tuners update converted to GTA IV with most tuning parts kept and fully usable, along with a moving steering wheel, all liveries and HQ & LQ interior variants.
I've included the .max project file for anyone who wants to make their own fully tunable car.

REQUIRES v65.0 or newer of Zolika1351's Trainer/Mod Menu to work, otherwise the car is completely unusable. v66.0 or newer recommended to avoid instability because of the high amount of tuning parts on this car.
PUT ZR350.DAT INTO THE "carmods" FOLDER! (if it doesn't exist, create a folder called "carmods" in your game folder and put the .dat there)

Use https://gtaforums.com/topic/955449-iv-zolikapatch/ to make the steering wheel move, unlock the 4 livery limit and make the popup headlights work

WARNING: Because of the high amount of tuning parts on this car, shooting at it is not recommended.

Vehicles.ide:
zr350, zr350, car, SUPERGT, SUPER, VEH@LOW, NULL, 50, 5, 0.2747, 0.2747, 0, 5, 1.0 ,0, sports+wheelangle:-18.198+popuplights+livery
txdp
vehshareV, vehshare
race_interior, vehshareV
zr350, race_interior

Carcols.dat:
zr350, 0,0,50, 3,3,2, 7,7,5, 13,13,13, 34,34,30, 33,33,29, 0,0,96, 40,40,41, 57,57,55, 70,70,71, 72,72,73, 77,77,75, 88,88,50, 104,104,107, 121,121,123

ZolikaPatch.ini (This is required to get the popup lights to have the correct opening angle) (Be sure to replace the "xx" with whichever number in the ini you want)
CarxxName=zr350
CarxxAngle=40

Tuning part count: 69 (nice)
Tuning part list:
Stock Front Bumper
Vented Stock Bumper
Street Bumper
Race Bumper
Cutout Bumper
Painted Cutout Bumper
Tuner Bumper
Stock Rear Bumper
Rear Diffuser
Primary Tipped Diffuser
Stock Hood
Ribbed Hood
Carbon Ribbed Hood
Ribbed Hood Alt
Carbon Ribbed Hood Alt
Cutting Vented Hood
Carbon Cutting Vented Hood
Trident Vented Hood
Carbon Trident Vented Hood
Kidney Vented Hood
Carbon Kidney Vented Hood
Fully Vented Hood
Fully Vented Carbon Hood
See-Through Hood
Carbon Stock Hood
Primary Louvers
Carbon Louvers
Stock Skirts
Street Skirts
Carbon Street Skirts
Tuner Skirts
Carbon Tuner Skirts
Race Skirts
Carbon Race Skirts
Vented Skirts
Carbon Vented Skirts
Competition Skirts
Carbon Competition Skirts
Custom Skirts
Carbon Custom Skirts
Extended Skirts
Carbon Extended Skirts
Primary Sunstrip
Plastic Sunstrip
White Fukaru Sunstrip
Black Fukaru Sunstrip
White Meinmacht Sunstrip
Black Meinmacht Sunstrip
White Powermetal Sunstrip
Black Powermetal Sunstrip
Optional Spoiler
Secondary Optional Spoiler
Street Spoiler
Carbon Street Spoiler
Tuner Spoiler
Carbon Tuner Spoiler
Race Spoiler
Carbon Race Spoiler
Competition Spoiler
Carbon Competition Spoiler
Big Wing
Carbon Big Wing
Rear Mounted Spoiler
Carbon Rear Mounted Spoiler
Rear Mounted Spoiler Alt
Carbon Rear Mounted Spoiler Alt