I desperately tried to upgrade to X 100D and although various DS said it is possible, this week I was told it wasn't . Please read some of the observations from the chief sales executive in U.K.
"f you go down the route of a 100D, you genuinely will only be adding approximately 20-25 miles extra range in the real world on UK roads, and it will have to be a completely new order, with delivery in July. In addition you won't be able to have free Supercharging for life, so it total the costs could run to approx 14k extra, plus the cost of using Superchargers?
Just this morning I've advised another customer of mine to go for Model X 90D instead of the 100D for exactly the same reasons - i.e. the extra 20 miles range is of little benefit for the extra cost, also bearing in mind as well how fast the UK & Europe new Charging sites are opening on a weekly basis."