This may not apply to the "natural leather" options, but I believe that most all automotive dyed leathers are treated with an invisible polymer-coating, which means in basic terms, you're sitting on leather that's coated with a microscopic layer of plastic. Over time, this layer can break down, but it greatly extends the endurance and lifespan of the leather.
Leather used for fine furniture and/or fine clothing/accessories is typically prepared differently, and has differing care requirements...
I pulled this text off of the I.M. Kelly website:
To most people 'leather is leather'. However if you think about the different uses for leather you will realise that the leather used for a handbag would be very different from the leather used in a luxury car. Even the leather used on furniture is unlikely to have the intensive wear and environmental challenges required of automotive leather.
Automotive leather has to withstand the wear and tear of clothing plus the effects of skin oils, sweat and even hair preparations in addition to the different temperatures and climate conditions across the world.
The development and production of automotive leather is a specialisation, and different types of leather are required for each type of vehicle. Leather used for a sports model with a firm seat that grips the driver is different from a luxury limousine. Automotive leather requires a high degree of knowledge and craftsmanship to transform it from a natural product into a high quality interior.
You can gather by insinuation, that there's alot of preparation and treatment going on with automotive leather, meaning that any "conditioner" you may use needs to be aimed at bolstering the health of the top surface, not the leather trapped underneath.
Myself? I've had the best luck doing what MMD does. Slightly damp towel OFTEN... Do not allow bodily oils and salts to remain on the surface of your seats for extended periods, wipe your seats often, keep them clean. That's it... Then, as long as you treat your interior gently, and don't murder your bolster on ingress/egress, you're good. My car is over 2 years old now, the leather looks no different than the day I bought it, and it's never seen a single "conditioner". Similarly, I've never applied any CLEANER to it either, as most cleaners are aggressive and will prematurely eliminate your protective coating. Drives me crazy when people toss soaps and chemicals where simple water is adequate.
The less crap you rub and scrub into your seats, the longer they'll last in my experience. I have to use fine conditioners on my antique cars, as the leathers are not protected whatsoever. But on modern stuff, it's a different strategy. If you do have to use a cleaner (grease), use a very soft cleaner.
For the rest of the interior, which really only gets "dusty", again, juts a very slightly damp towel is all I ever do. Don't use a cleaner to "dust" forchrisake. I love it when people get in my car for the first time, and ask me if I just bought it....
