Teach her to use a firearm. There's a way you're taught, a long series of rules and rituals, for doing it safely: i.e. for doing that and avoid the possibility of killing someone. IMO something about the recoil on a battle rifle makes it abundently clear, visceral, that it would be lethal and that you never take chances with it -- so for example always check to see if it's loaded when you pick it up even if you "know" it isn't.
I'm conscious when I drive a car, that I'm handling a dangerous and potentially lethal "weapon".
Alternatively, teach her to use a bicycle. I think I've become more sympathetic towards other road users (including cyclists, pedestrians, children, dogs, horses, tractors) since I started to cycle regularly. For bonus points, get her to use clipless pedals ... they're more efficient (make you a better cyclist). Also I'm told you inevitably fall over a few times when learning to use them (usually at zero miles an hour, when you come to a complete stop and forget to unclip in time) ... which, is a good reminder that even a mild accident can hurt a bit, and that an accident at 20 mph would hurt too much.
One more thing, it might be worth telling her that you can't afford to take risks when driving. If she's like me then the thought will occur to her sometimes, "I can probably overtake before the next bend", or, "There's probably nothing stopped in the road just around this next corner", or, "That car that's speeding toward the intersection will probably slow down and stop when it gets there", etc. But "probably" isn't quite good enough. If something has a one-in-a-hundred chance of going wrong, by the time she will have driven for a few decades she will have done it a thousand times. You have to be certain, you have to see the empty road that you intend to drive on, and slow down for a "blind" corner.
Speaking of blind corners, I read once that every line of the Fire Code is "written in blood". What that meant was that, if there's a line in the Fire Code which says that "a basement apartment must have a window big enough to escape through", that's because somebody died when there wasn't one. Similarly if the Traffic Code says "don't park close to an intersection" or "don't overtake a school bus when its lights are flashing", that too is written in blood. Obey the Highway Code, to avoid blood.
Finally, it's one thing to risk her own life; another thing to risk your car, or a fine, or criminal record, or your car insurance. But what she's doing if she's speeding is risking other people's lives, other people's health forever: and they're not hers to risk, she's shouldn't feel entitled to risk them.