One of the reasons I went back to a Series III is that it is “the most modern of all antique automobiles”. As impressive as the the X300 is it lacked that “olde world” feel that I had grown fond of in the older models.
My X300 was the supercharged version, the XJR. Black on black. It had a performance-oriented feel and plenty of oomph.
The X300 and XJ40 are closely related and have a similar feel, IMHO.