Speed change rails for Minecarts

I have had this idea for a while and truly believe it is a large part of what would fix Minecarts. Instead of having a global max speed, have a rail that when crossed, sets the max speed of that Minecart. Having a gamerule you need to change is clunky, and making it universal to all minecarts is weird. Minecarts are too slow for long stretches, and when sped up, too fast for small areas like train stations. What I picture is getting on the minecart, it goes normal speed till you hit the rail, then takes off, then when arriving at the other station, slows back down after crossing another speed change rail. It would allow plays to choose what speed minecarts go at which parts of their tracks, and only be per minecart. Default speed would stay the same on newly placed minecarts, so redstone machines wouldn't be affected.