Re: 156 Sportwagon... Petrol or Diesel???
I have a six yr old sportwagon 2.4jtd veloce.
I have driven 164 3.0 12v cloverleaf and 24 valves also.
The JTD torque is much more impressive than the 3.0 164's, but of course it runs out at 4.5-5k (with mods), unlike the 24v which is only just coming on cam at around 4k.
The 3.0 164 is a good car, especially in cloverleaf form.
My alfa with spirited driving returns 36/37mpg.
Out and out the 164 3.0 is much faster, but the 156 is great fun with bags of torque, but the gearing is somewhat different.
Heavy engine, and even with veloce sports suspension its far too soft on the front, need KONI sports kit to make good fun - £400, then needs 17's to make use of the suspension.
brakes aren't great and need decent discs and semi-race/track pads if you want to stop it from v-max speeds - EBC yellowstuff are good if a little noisy.
Quickish to 120mph on the straight, get a slope (downhill) and you may get 135mph on the clock at close to the redline - not the sort of performance a good 3.0 would give - 140mph with ease!
Sounds good, 5 cylinder, but so does a 5 cylinder VW LT35 van. (don't take that the wrong way - most 5 cyls sound good)
Intercooler is cr*p, and in a really bad location, going FMIC will get you an extra 500 revs top end you never saw before in the car and getting rid of those stupid bends in the intake and getting a cone filter in the area the intercooler was (straight pipe) helps out breathing.
For me, 164 cloverleaf is where I would put my money if I could run an older car for work - stuff the economy, 22mpg from a cloverleaf is better than the 15-16mpg I get from my supercharged Jag!
All in all, JTD 2.4 is great fun and has a lot to offer, but I found myself modding too many comprimises (handling, intercooler, breathing, boost etc) to make this car 'good' for performance and handling - Still an ongoing project.