I've owned my 325 for a while now, and I've gotten most of the major deficiencies sorted out. I'd been wondering about the leather-covered factory steering wheel all winter. The finish was wearing off the leather, so it was becoming brown instead of black, and getting really sticky and gross in the summer (I tend to have sweaty hands, which doesn't help).
When the warm weather arrived and my gloves came off, it was time to do something. I love easy solutions, so for a while I've been polishing my shoes using a shelf-shining liquid shoe wax called Kiwi Elite. It's the kind that comes in a little bottle with a sponge applicator. It looked really good on my shoes and is waterproof, so it won't mind sweaty hands. After spending ten minutes rubbing my hands all over my shoes to be sure it wouldn't come off (who wants to get black-handed every time you drive?), I decided to give it a try on the steering wheel. IT WORKS GREAT!
It took a couple of coats to get a really good finish (the first coat just sucked up into the raw leather I guess), but now the steering wheel looks beautiful -- a nice, deep, shiny black, just like new. I've had the stuff on the wheel now for a couple months, and it's never rubbed off on my hands, and still looks great (I did add a new coat after I scratched the finish with my thumb nail during some rather spirited oversteer once).
So for a new life for old leather wheels, give the Kiwi Elite a try (make sure you break the seal on some shoes or something first though -- when you first push down on the sponge to break the seal tab, the stuff comes gushing out).
Happy steering!!