maybe ST+RIDE? But I don't see how that matches "speed"

Either COURSE or STRIDE. @ffao STRIDE fits better (synonym for pace or speed).

... DESIRE ddef? Not sure how that matches speed either

@Deusovi was @ffao correct?

@ffao That's correct.

(Sorry for the delay.)

A neat little CCCC that one

I wish I could've removed the space in "street car"

probably would've been semi-acceptable, but I decided to leave it in because I wasn't going for a particularly tricky clue

CCCC: The end of the waking hours is now, after summer's conclusion, close to pitch-black (4)

^ I don't know how valid this is, but it shouldn't be hard enough to matter, I think