I'm surprised you don't get more than that. I tend to get 22 and change, my girlfriend is consistently exceeding 24 mpg with her Redeye.
And that's on anything but flat and certainly not obeying the speed limit. Either of those does work against an EV, but the elevation changes (thousands of feet, usually), we can't do much about.
At one point the local Porsche dealer offered to bring a Taycan by for us to look at, but ended up admitting that it wouldn't make it the 150 miles to here (it's supposed to go about 240 miles). And that's ignoring that he'd need at least a bit of electricity to make it back down to the dealership again.