I get 30 mpg and I am a bit of a led foot. Speed ? I did get 90 out of it but I ran out of road and I had plenty more throttle left ,I would say over a ton. the top comes down in seconds and up in 30 seconds,unless you are having a cloud burst then it takes about 2 minutes (I'm kidding). their are many Miata clubs around ,that have rally's and track racing, I was going to join the Portland club but these guys go on these tours and get togethers but they stay at real fancy hotels $120 a night at least, to rich for my blood,they seemed a bit snobby to me ,and I had enough of that sh1t in England. so I make up my own tours,after all I am at heart a motocyclist and a loner by nature. you guys are my only friends,all many miles away,suits me fine.
So far I cant tell you about maintainance I have never had a problem.
you know I am a fannatic about oil changes,and do it every 2000 miles,including the manuel gear box ,transmission to you guys.
I think you wife will love it ,and so will you,Oh ! and it handles like a dream, buy one ,enjoy one, do some quiet shopping so you have one by spring time.