I put an aluminum wheel on my 2.3 car.
Around town, it accelerates a little faster, decelerates a little faster.
On the highway, it gets about 2 mpg better fuel economy on average. 27 to 29 and change. Still trying to coax 30 out of it. Little turbo engine. The N/A engine managed 34 before it needed to come out.
I haven't had it on the track. Yet. Engine out again due to leaky oil pan. If it ain't one thing it's another on these 2.3's.
Have a Fidanza wheel on my 427, T56 as well. Can't tell much difference between it and a steel wheel other than it seems to free rev a little quicker. With a big heavy crankshaft like the SBF, you don't notice the "typical" differences like needing more RPM and clutch slippage to keep from killing it from a dead stop. I've never noticed that and I've had several SBF's with aluminum wheels. The only time I've really seen a difference was with a circle track style 7" multi-disc clutch and an UL flywheel. VERY quick to rev, also easy to kill it, but that setup was like 12 lbs total including the clutch.
'92GT, 427" and '93 "LXVO" coupe