They need to use that sweetener that Coke uses in some diet drinks in Europe. Cyclamates.
Looked up cyclamates. Wikipedia says that they usually mix it 10:1 with sacchyrin (which is ten times sweeter, so it’s 1:1 as far as sweetening effects go). Supposedly, it’s to minimize the bitter taste of both sweeteners. Anything that has to be mixed with sacchyrin because it’s too bitter on its own... yuck! Sacchyrin is NASTY! I’m not talking about its dubious alleged carcinogenic effect; I just mean it tastes AWFUL.
So why does Europe really use cyclamates? They’re the cheapest sweetener out there.
Cyclamates are banned in the U.S., having been reviewed by the FDA under four different commissioners, including under the Nixon, Carter and Reagan administrations. The U.K. and Philippines reversed their bans on cyclamates.