Answer: sleekest

AnswerCrossword Clue
SLEEKESTMost aerodynamic
SLEEKESTStreamlined to the max
SLEEKESTMost glossy
SLEEKESTBest groomed
SLEEKESTLeast wind-resistant
SLEEKESTSmoothest
SLEEKESTSuperlatively streamlined
SLEEKESTMost well groomed
sleekestSLEEK, smooth and glossy, also SLEEKEN
sleekeststreamlined
sleekestsmooth and glossy
sleekestto make sleek