Heya, welcome to the site
Theres two types of S15 in case you didn't know, Spec R with a Turbo and additional support braces and the Spec S which is N/A
Bought a Spec R myself back in March and still getting the hang of it.
MPG for a spec R is at least double figures depending upon how you drive, 20-30 rough guess but my foots pretty much planted to the floor all the time and it is a sports car so im not too bothered otherwise i would have brought a clio. Having said that it is not as bad as an RX7 tho.
Oem spare parts are normally found on the importers websites and the guy u import from may be able to help, There's companys that make the oem parts too which are better value like air/oil filters. Supposedly the replacement performance parts are cheeper than oem replacements from what i've read imo.
Look at Blue print for the oem replica parts for maintance and these two for importing performance parts
http://www.nengun.com/
http://www.rhdjapan.com/
Maintance itself is pretty straight forward if u have your own car jack, oil & filter every 6000 according to the manual thats been uploaded here, some ppl do it sooner but it depends on how u drive it.
http://forum.s15oc.com/showthread.php?458-Nissan-Service-Sheets
http://forum.s15oc.com/showthread.php?5-S15-Service-Manual
In terms of insurance, not sure about the group but I would guess a ball park figure of £700 - £1300 for a spec R and dependent on your driving history.
I got mine taxed as a PLG when it was imported since they dont have an emission's report for the car and i believe that is still the norm. Tax would be 112.75 for 6 months & 205.00 for a year
Other than that your your tyer & brake pad wear depends on how you drive it and i wouldn't be able to guess that (haven't changed mine yet tho in 6 months) and fueling your looking at 97Ron super unleaded to start with but i use 99Ron Super unleaded and would recommend the same.
Tyres are about £50 - £150 depending upon whom you go to and which manufacturer
Have a look at this site, specs of the car that were made
http://nissans15.com/spec.htm
hopefully if anything above is worng someone will point it out :notworthy: