Guys, if you just want to clean up dirty seats - light coloured ones like beige...
I just cleaned my whole interior... with soap and a brush. Very easy.
1. insert some cloth into seat crack to catch moisture.
2. Wet yr hands in the pail, and wet the leather accordingly.
3. Scrub the brush on the bar of soap (I used Cussons Imperial Leather, haha) to pick up bits of soap
4. Scrub away at the leather. Yes, leather will be wet, and the scrubbing with the soap WILL bring out all the dirt. Leather is cow skin, and its just like bathing your pet cow or pet pig with a brush and soap. If you wanna know whether the brush is too harsh or too stiff and will hurt the leather, try using it to scrub your forearm with the water and soap. If it doesn't cause you lots of pain, your pet piggy won't complain too.
5. Sprinkle more water on the soapy parts accordingly, but do not over saturate the whole seat with wetness. Do one portion at a time.
6. To wash off the soap, take use a wet cloth and wipe off the excess soap. Wash soap off in pail of water, and wipe soap again. To check that you have removed all the soap, use a wet finger to 'test' the surface. You should know by the feel of friction.
7. After cleaning off the soap, the leather would have absorbed quite a bit of moisture. That's actually ok. Leave the car in the sun for 30 mins for some of the water to evaporate, and then moisturize the leather with a creamy leather treatment. I used the autoglym one - no complains.
I have been living with a full light beige interior that is 5 yrs old, and still looks fresh and new.
I tell you, using soap and brush beats all those leather cleaning products I have tried. This simple method is faster, and way more effective than my first 6-9 months of mindless rubbing with various expensive brands of leather products.