If the car was well maintained hopefully you have some maintenance records. Most of these maintenance jobs are pretty easy and not costly. My car is a 2000 115k on the car I started having problems on acceleration and it was the fuel filter. The filter is cheap but it is a little more difficult task a few hours work at most. The other issue I had was my car went into restricted performance and by cleaning the MAF and the throttle body it was resolved. The XK8 is a pretty high maintenance car. To clean the MAF you just need to take off the air intake and the TB can be cleaned on the car at that time. Of course the air filter could be done at this time. Plus adding a little fuel cleaner in the tank could be helpful. This should make a difference. As far as plugs go NGK or Denso but hopefully they were changed. Again if the alternator is not putting out around 14 volts that could impact performance also.

If the transmission is shifting smooth then don't worry about it. Changing the fluid in the ZF 5 speed can be tricky.

 

Got it. Putting Mustang seats in my XK will make it "faster". Ideally w/ a Galloping Horse logo. Much easier than adding a supercharger and less maintenance.
Full throttle engine sound effects in the stereo when the accelerator is pushed quickly? Tesla has some unique sound effects. You may not want some of them in your XK

 

I have a 2003 xkr and from my experience it does “feel” slow to accelerate. You really have to play with the throttle and be in the right gear for it to throw you back. If it’s in “D” and you are casually cruising and decide to step on the gas the car will feel slow until it gets up to RPM which sometimes takes “forever” and then it gets scary. I noticed if you step on the gas, let go, and then step on it again the car will find a lower gear to accelerate faster in. Still plenty fast for me but comparing my XKR to other vehicles the acceleration definitely “feels” slow due to the smoothness perhaps? But even my slow/regular cars “feels” faster in acceleration due to their engines working harder? That’s my experience. Hope that makes sense, for example in my old Toyota tacoma 5 speed it might take me 8 seconds or however long (never timed it)to get to 60 but the kick back feeling is way more apparent