If you drive over multiple power ups in one turn you only get credited with 1 of them.
See example below, player 1 goes over 2 Boost powerups but powerups only increased by 1
(Sidenote: I also expected that driving over multiple Mud cells would each decrease my speed.)
round:10
player: id:1 position: y:4 x:68 speed:9 state:TURNING_RIGHT boosting:false boost-counter:0 powerups: OIL:1
opponent: id:2 position: y:3 x:76 speed:9
[░░░░░░░░░░░░░░░░░░░░░░░░░░]
[░░▓░░░░░░▓░░░░░░░░░░░░░░░░]
[░░░░░░░░░░░░░2░»▓░░░░░░░░░]
[░░░░░1»░»░░░░░░░▓░░░░░░░░░]
C;10;NOTHING
C;10;ACCELERATE
Completed round: 10
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Starting round: 11
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round:11
player: id:1 position: y:4 x:77 speed:9 state:NOTHING boosting:false boost-counter:0 powerups: OIL:1, BOOST:1
opponent: id:2 position: y:3 x:85 speed:8
[░░░░░░░░░░░░░░░░░░░░░▓░░░░]
[▓░░░░░░░░░░░░░░░░░░░░░░░░░]
[░░░░░░»▓░░░░░2░░░░░░░░░░▓░]
[░░░░░1░▓░░░░░░░░░░░░░▓░▓░░]