The best spot is marked in red, but only if the infantry commander's hatch is open. However the driver could forbid this. Old vehicles could have a bad rubber seal, and once you open that hatch, it will leak during rain. Drivers slept on their seat and the seat of the infantry commander, and nobody wants to get wet. Further down the list: orange and yellow. Riding atop the front of the turret is good. You can sit well and see well. Light green is good when the BMP is fully functional and the wind is not coming from the front or the right. A BMP that's acting up could spew oil from the exhaust collector, and when the wind is blowing, you end up breathing in the exhaust.
Red with a stripe is worse than riding on the front of the turret, but it will do. If nobody is sitting on orange, you can lean on the turret, and it's easy to hold onto the gun when the vehicle lurches. Others say that they would place a seat from a car here, and it would become the best spot.
Blue: sitting behind the turret is inconvenient, as you're sitting against the direction of motion, and during the summer dust gathers there like with a vacuum cleaner and causes you problems. Yellow with a stripe: you can lean on the turret and hold onto the gun, but the proximity of the exhaust times the direction of air makes a significant drawback.
Black with a stripe and blue with a stripe. People sat here when the BMP carried one to two squads at the same time. It's uncomfortable (there is nothing to lean on with your back) and you feel the vehicle lurching more strongly.
Black, purple, gray, white: we tried not to sit here at all. In the first two, sitting against the direction of motion is uncomfortable, and during the summer you will choke on dust. The gray and white spots can only be occupied when the rear hatches were open, but this is not allowed, as dust will collect inside the vehicle. On old vehicles, this also causes leaks (the rider compartment was also used for sleeping, and nobody needed water pouring in).
The worst option is green with a stripe. Sitting right next to the exhaust causes a torturous pain in your eyes and difficulty breathing.
The gunner sits in the green spot and the commander sits on the light blue spot."