I have a 1.8 Mk2.5 in blue that looks to be exactly the same spec as the one linked in the OP. Its a fantastic motor. Depressingly I paid a good 2k more than that about 6 months ago but it was from a main dealer and had done half the mileage along with 12 months MOT / Tax / Warranty etc so I suppose its not all bad
It's a cracking car and looking back I wouldnt pick any spec but the 1.8 sport. The heated leather seats are lovely if you want to have the top down when its cold out. The 6 speed gear box is a joy and makes me think I'm handling a bolt action rifle with every gear change. I have to admit though, its not a hugely quick car (though it does feel fast when your pressing on due to being so invovled in the drive) so I wouldnt step down to the 1.6 myself as its a fair bit slower.
In the 6 or so months I've had mine the only problems I've had was one of the rear drain holes clogging up, which was easily solved with a long thin screwdriver, and the switch in the drivers side door for the interior light conking out. This was solved simply by removing the switch and reattaching the cable where it had worked loose at the back. Other than that it hasn't given me any problems in the time I've owned it.
To give you a true idea of MPG this is how I'm getting on at the minute
http://www.fuelly.com/driver/binnsy/mx5-miata, its worth noting that the bulk of my driving is short trips to work and back. My current tank is going to be more around the 32MPG at a rough guess on a tank that has been split evenly between short trips, and a 120 mile cruise at 60ish. I imagine 35MPG would just about be doable on a long run.