I think the 88s-89s offered more features with the CRT and that incredible 1/4 tank fuel gauge feature. That being said, I just sold my 88 and I have two 90s. A vert and a parts car coupe. My first 88, I had to replace both the CRT and the IPC. I think the 88s-89s offered more unique options with the CRT that the 90-91 didn’t get like setting reminders and the calendar option. Speed sensor and mpg. I love the 90-91s but when you sit down, it’s a totally different feeling looking at the round dash versus the square dash. Dave McIntosh this summer at the BCA meet said he preferred the rounder dash of the 90-91s as he thought it fit better with the curvy nature of the car. I get that but I love the boxy square design of the 88-89s. I think it was so unique and special. I might end up trading my 90 vert for a good condition 88 or 89 as I adore those models.