I've only seen WRX's and STI's attempt to autocross, never ridden in one, it didn't look pretty, or fun. As a practical car first, sporty second, turn it in before you need to start doing major maintenance they seem great. As for actually flogging it on track they fall pretty far down my list, I'd honestly take an Impreza (or Mazda3) over an STI at this point, put the $15k in my pocket towards something else.
Been hanging out with the BMW crowd, the E46 looks great on paper, but that is one of the cars that has garnered BMW's current reputation for expensive repairs and potential unreliability. It only makes sense if you are totally comfortable paying maintenance bills on a car that was, and always will be, a ~$55k+ car in 2001 money (>$73k today's bills) OR working on said >$70k machinery yourself. Same story with the M5 and pretty much any Bimmer built from the Clinton-era onwards, if you've got the money they're hard to beat, not many people have the coin.
I have driven an IS300 and the suspension even on the beaten and abused model I drove was sublime, double wishbone all around, 3.0L straight six even through the AT and carrying an extra 500 lbs totally out-torqued the FA20. Same lead engineer as the AE86 and it shows, it's basically a Toyota E36 M3 on paper that came out 5 years too late.
But I can't shake the fact that none of these cars really tick the boxes for being practical enough, modern or reliable enough as a family car imo. Except for the M5 the rear seats are all rather tight and to track all of them it will be a very slippery slope, oh just brakes and tires, well to preserve the tires I need camber and with the camber lets just stick with MPSS but I should save them so second set of wheels so lets go bigger and power and coilovers and on and on until it's uncomfortable and impractical. IS300 gets close, I think a set of modest tires, brakes and a good alignment could be sufficient, but it's a 15 year old sedan, I have a hunch the magic will wear off unless you can really work the suspension on a regular basis.
http://www.caranddriver.com/comparis...omparison-test
Mazda 3 (and hatch>sedan for the record). New Civic might have upped the game, but it's a first model year for Honda's new turbo four, might not be the winner today but maybe in a year or two.
http://www.roadandtrack.com/new-cars...c-first-drive/
http://www.edmunds.com/honda/civic/2016/road-test/
I think @
DarkSunrise is right, small, fun, practical DD cars are the right solution, check out current hatches. Problem is as far as I'm concerned all of those have mediocre rear space as well, might be ok for him but it's tough. New Civic, Mazda3 and 4-door Golf/GTI would be my top three suggested test drives. Not as fancy or punch packing as OP's original list but more fuel efficient (should all be >30 mpg average), newer (warranty, parts aren't worn out requiring expensive repairs), safer, and reportedly can be very fun.
Mazda3 w/ 2.5L and a Manual should be orderable, from what I've heard though that extra 0.5L isn't really worth the money and loss in fuel economy.
Edit: After writing that, maybe instead of going supercharged on my 86 in a few years, I could pick up a Civic-R as a all-rounder family car... If it's actually as good as the hype says they are.