Just wanted to hear some thoughts on this vehicle..Thanks, Matt
I think it was a letter from me that got the thing classed in the first place (I have a thing for quirky hatchbacks), and I was going to build one, but was unable to find a suitable donor vehicle at the right price to turn into a race car. I race a Z3 1.9 now, which is basically the same thing (engine, drivetrain, suspension) in a different body shell. There were a number of Z3s raced in SSB, so I was able to find a "race ready" platform that I converted into an IT car (rather than building a car from scratch).
My general comments about the platform (either one):
On paper, it looked to be a decent place to start, but there is a lack of "off-the-shelf" aftermarket support for either the M44 motor (which all the Z3s and the '96+ 318tis have) or the M42 motor ('95 318ti). Any real power improvements will require a fair bit of custom work. Note: I have not investigated aftermarket ECUs, and am unlikely to do so - the cost/reward ratio doesn't seem to be worth it for me as I don't think the Z3 will ever get down to the times I'm seeing put down by other cars at my "home" track, even if I ship cubic dollars to somebody for a Motec and the countless dyno hours tuning would require. I've also got some issues with transmission ratios - HUGE gap between 2nd and 3rd gear which is prompting me to go fairly radical in final drive choice for decent performance gains at NHMS (which means I'll need to change gears for longer, higher-speed tracks). The 4-cyl BMWs are also on the heavier side at 2,600 lbs, so even if the power-to-weight ratio is there, it's tougher on tight tracks to toss the thing through the corners like the Hondas (or Miatas).
That said, on longer tracks, if you can get the power out of the platform, it could be a contender, but the tighter the tracks get, I think the more things get stacked against it.
If you like 4-cyl BMWs and like ITA, the E36 318i/is has the multi-link rear suspension (the 318ti/Z3 have the older E30 trailing arm setup in the rear), but I've only seen one of them here in the Northeast. If you want to run at the front of ITA, I'd look at a different platform.
Just my view from mid-pack..