I couldn´t find any correct information on all the bonuses available in the game anywhere, so for the sake of completeness I have tested the conditions to get the bonuses:
- Insane Stunt Bonus! ($ 1 000): Stay in the air with your vehicle for about 1.2-1.3 sec. Speed should not go below 100 when the bonus registers.
- Back-To-Front Bonus! ($ 1 000): Drive backwards for one minute with at least a wanted level of 4. Letting off the gas or reaching zero speed resets the counter.
- Accuracy Bonus! ($ 5 000): Hit pedestrians with 25 bullets, rockets or molotovs without missing. Hitting a (wrecked) vehicle doesn´t reset the counter. Additional info: Shotgun shells count as 5 bullets, but reset the counter if the full spread doesn´t hit a ped or (wrecked) vehicle. Using Grenades, Vehicle Mines, ElectroGun and getting wasted/busted doesn´t reset the counter. Using a Flamethrower resets the counter instantly while the water/fire cannon of the Fire Truck resets it only when either peds or a (wrecked) vehicle are hit.
- Cop Killa! ($ 5 000): Destroy 20 Cop Cars in one session. Reload resets the counter.
- Medical Emergency! ($ 10 000): Destroy a Medicar, Fire Truck and a law enforcement vehicle (Cop Car, SWAT Van or Special Agent Car). Timeframe between destroying two vehicles should not exceed 5 sec and the order in which they are destroyed doesn´t matter.
- Car Jacka! ($ 10 000): Hijack 100 vehicles in one session. Hijacking means throwing the driver out of his car, you don´t need to enter the vehicle. Reload resets the counter.
- Elvis Has Left The Building! ($ 30 000): Kill a group of 6 Elvis impersonators (those guys in white overalls) in one combo. Timeframe between two kills should not exceed 0.5 sec.
- Genocide! ($ 30 000): Kill 1000 people in one session. Reload resets the counter.
- Grand Theft Auto! ($ 30 000): Hijack one of each vehicle models that can be found in traffic (see car list below). Emergency, law enforcement, military or gang vehicles and the bus don´t count. Reload resets the counter.
- Wipe Out! ($ 50 000): Destroy one of each vehicle models that can be found in traffic (see car list below). Emergency, law enforcement, military or gang vehicles and the bus don´t count. Parked vehicles do count and reloading resets the counter.
- Expeditious Execution! ($ 100 000): Kill 20 people in one combo. Timeframe between two kills should not exceed 0.5 sec.
- Wang Car Bonus! ($ 100 000 + 8 bonus cars): This bonus exists only in the residential district. Collect all 8 GT-A1s (those cars with numbers on their roof). Each car gives you $5000 and the last collected car $100000 and 8 special vehicles (4 Furore GTs with either oil slicks, vehicle machine guns or vehicle mines. An Armed Land Roamer, a Special Agent Car with vehicle machine guns, a Tank and a Fire Truck with a fire cannon) at the Wang Car garage. A game bug respawns all cars after save/reloading in version 9.6 and probably earlier versions too. Collecting a car, save/reloading and collecting the same car again gives you the bonus instantly in those game versions.
Car list for traffic vehicles:
* car can be found on a parking lot
* needs to be unlocked via the yellow Loony mission "Dimentia To Go!"
- Downtown (19 vehicles): Aniston BD4, B-Type, Beamer, Big Bug, Bug, Dementia Limousine, G4 Bank Van, Ice Cream Van, Michelli Roadster, Minx, Romero, Schmidt, Shark, TV Van, Taxi, Truck Cab, U-Jerk Truck, Van, Wellard
- Residential (22 vehicles): Arachnid, B-Type, Benson, Big Bug, Bug, Eddy, Furore GT, G4 Bank Van, Hachura, Hot Dog Van, Maurice, Morton, Panto, Schmidt, Spritzer, Stretch Limousine, T-Rex, TV Van, Taxi Xpress, Trance AM, Truck Cab SX, Van
- Industrial (23 vehicles): Arachnid, B-Type, Big Bug, Box Truck, Eddy, G4 Bank Van, Garbage Truck, Hot Dog Van, Jagular XK, Jefferson, Maurice, Minx, Panto, Romero, Rumbler, Shark, Sports Limousine, Stinger, TV Van, Taxi Xpress, Truck Cab, U-Jerk Truck, Van
Some additional notes:
- The condition to get the Insane Stunt Bonus is not so clear. The distance you fly doesn´t seem to matter, but I noticed that it always registers between 1.2-1.3 sec and if the speed was below 100 it didn´t. Not sure if you constantly need to stay above 100, bumping into a car and get a speed boost right at the 1.2-1.3 sec mark might be enough to get it.
- For the Elvis bonus, it might register even if another ped is killed inbetween as long as it is in one combo (<= 0.5 sec between kills), but I didn´t test it.
- Getting busted/wasted doesn´t seem to matter for any of the long term bonuses.