dangerous
unsafe
abrupt
accident-prone
agile
bluff
bold
breathless
careless
daredevil
dashing
desperate
devil-may-care
double-quick
eagle-winged
excessive
expeditious
express
fast
fleet
flying
furious
galloping
hair-trigger
harum-scarum
hasty
headlong
hell for leather
hotheaded
hurried
hustling
impetuous
impulsive
light of heel
light-footed
lively
mad
mercurial
nimble
nimble-footed
overeager
overenthusiastic
overzealous
panting
plunging
precipitant
precipitate
precipitous
prompt
quick
40-minute
all-day
balls-to-the-wall
bone-jarring
five-mile
forty-mile
forty-yard
full-out
heart-stopping
hyperlight
hypersonic
lost
near-light
perzonal
roller coaster
sixty-mile
suborbital