Having trouble seeing the brake lights in the broad daylight, running lights/turn lights? Try this suggested settings. You can adjust the level of brightness on each light to suit. 

Go in visualsettings.dat (update.rpf/common/data) and find these lines, then replace them:

# emissive bits
car.headlight.day.emissive.on    50
car.headlight.night.emissive.on    10
car.headlight.day.emissive.off    0.003
car.headlight.night.emissive.off    0.001
car.taillight.day.emissive.on   50
car.taillight.night.emissive.on    20
car.taillight.day.emissive.off    0.003
car.taillight.night.emissive.off    0.001
car.indicator.day.emissive.on    400
car.indicator.night.emissive.on    200
car.indicator.day.emissive.off    0.003
car.indicator.night.emissive.off    0.001
car.reversinglight.day.emissive.on    40
car.reversinglight.night.emissive.on    40
car.reversinglight.day.emissive.off 0.003
car.reversinglight.night.emissive.off    0.001
car.defaultlight.day.emissive.on    2
car.defaultlight.night.emissive.on    2
car.defaultlight.day.emissive.off    0.003
car.defaultlight.night.emissive.off    0.001
car.brakelight.day.emissive.on    100
car.brakelight.night.emissive.on   50
car.brakelight.day.emissive.off    0.003
car.brakelight.night.emissive.off    0.001
car.middlebrakelight.day.emissive.on    50
car.middlebrakelight.night.emissive.on    50
car.middlebrakelight.day.emissive.off    0.003
car.middlebrakelight.night.emissive.off    0.001
car.extralight.day.emissive.on    9
car.extralight.night.emissive.on    9
car.extralight.day.emissive.off    0.003
car.extralight.night.emissive.off    0.001
car.emissiveMultiplier 2

Original settings by Cj24