I have to agree with the passenger space in the back. I'm a tall person and when I drive my seat is all the way back. When I have passengers, I have to drive very uncomfortably so that the person behind me has leg room. There is no way that this car can be made into a 5 seater, I've squeezed 3 people into the back before, and I mean squeezed. I could barely close the doors and they were average sized people. Best keep it as a 4 seater.
Also, back then the KE30 was the smallest car Toyota released in the country. It would have been the equivalent to out Yarris today. A budget small car, small, basic and cheap.
As for the vinyl seats, I actually like them. I love the look. You kind of get over the coldness in the winter and pain in the summer (just wear a shirt).