The digital speedo on the 1st gen is incredibly slow.
On my '17 BRZ the digital speedometer only updates a couple of times per second.
The only sport car I've seen with an even slower update rate of the digital speedometer is Corvette C7.
For comparison, the data on the CAN bus of FT86 is available at 50 updates per second.
Here's how a speedometer with 25 updates per second looks like:
It's way more responsive than the digital speedometer in your car, isn't it?
I'm pretty sure 25 updates per second can be achieved on any modern screen that's not e-ink.
Re: "the car doesn't accelerate that fast!!!11"
It does brake fast enough though.
Unfortunately, the way the speedometer works on the 1st gen I can't really trust it when I brake into a corner at the track and only have a fraction of a second to glance at the screen (a habit I developed in sim racing).