After shooting Quilty in Chapter 35, Humbert in chapter 36 has been driving on the wrong side of the road (‘not exceeding 20 miles an hour’), then, when he sees two police cars blocking his progress ahead turns off as in the quote above with ‘two or three big bounces’, surprising some cows and comes to a ‘gentle rocking stop’ on a grassy incline.
Humbert himself has not hit a pedestrian in this nor indeed any other chapter (though his actions might be said to have led to Charlotte being run over by the car in Chapter 23 p 98).
The reference to “the two dead women” arises in relation to Charlotte Haze’s death by motor vehicle collision and a second murdered woman (Dorothy Grammar) mentioned in Chapter 33 pp 287-88:Her spouse had bludgeoned her to death and then placed her dead body inside a car which sped down hill, sideswiped a pole , ran up an embankment and then overturned , he had contrived to make it appear her death was the result of motor vehicle trauma.
Hegelian Synthesis linking the two dead women :
Hegelian synthesis refers to progressive advancement in ideas/understanding when contradictions are considered and a new understanding emerges: this has found popularity as the triad of Thesis , Antithesis and Synthesis.
Applied to our context:
The car ‘apparently killing’ Dorothy Grammar speeds down a slope sideswipes a pole and stops after rolling over, (but the injuries arising from bludgeoning) did not match the expected injuries from motor vehicle trauma; hence Edward was tried for murdering wife.
Charlotte Haze is killed when struck by the Beale’s car as she tries to post her letters and the car drags her for a few feet then comes to a halt on an incline. And she did die because of this motor vehicle collision in which Humbert had no involvement thus leaving no incriminating evidence to point to Humbert leaving him at liberty to take advantage of the situation to further his evil motives.
In the quote Humbert drives off the road and does come to a stop on a grassy slope mirroring the motor vehicles involved in the two deaths.