These days, used prestige performance cars are so cheap you could easily find yourself steering a retro rocket. But when it comes time to look inside, you might see something that's completely foreign to you in car interiors - leather.
Leather is a strange stuff. Made from cowhide - but with a whole lot of steps along the way - it's a natural substance that responds in a very different way to vinyl. It's likely that an older car with a leather interior will be showing seats and door trims that look a bit faded, a bit dry and stiff. There's basically nothing that you can do about vinyl that's in this condition, but with leather it's possible with the right conditioners - and a lot of patience - to bring the material back to looking near new.
Magic? You'd better believe it.
But whatever you do, don't apply vinyl restorers or treatment to leather - it'll make it look a whole lot worse and may even cause irreparable damage.
The first step in restoring the look and feel of a leather interior is to clean it. Dirt is highly abrasive and will hasten the wear that the leather is experiencing. That's especially the case if you rub the dirt in when you're applying conditioner - which is why a thorough clean is the first step.
Dedicated cleaners are available for leather and these should be used. As the first step, try the cleaner out in an unobtrusive spot to make sure that the leather remains colourfast with that particular cleaner. All automotive leathers are dyed - you don't want to dye coming off as you clean...
Apply the cleaner to a damp sponge and gently rub it in a circular motion on each leather panel, trying to prevent it from seeping in along the seams. Leave for a few minutes and then wipe off with a damp, soft, lint-free white cloth. The cloth should get grubby fairly fast (that's the dirt coming off) so change it frequently.
If the dirt is ingrained (especially on light coloured leathers), a nail brush and soapy water can both be sparingly applied.
The major step in restoring the look of leather is in the conditioning. Leather conditioners contain waxes and oils that are absorbed by the leather, bringing back the look and feel. However, they come in lots of different 'strengths' - what you use on leather in good condition isn't what you use when you're trying to bring something back from the dead.
Typically, the leather conditioners sold by car manufacturers are very mild. For example, BMW sell a leather conditioner which is excellent on good condition leather. It's also quite cheap. However, applying just the same stuff to leather that's dry and old will result in the leather conditioner disappearing into the surface - and no apparent change to the leather.
What's needed is something aimed at worn surfaces. Mothers Leather Conditioner is a good next step, suitable for most leathers that have had a few years pass under their belts (or bums sitting on them, for that matter.) But in really tough cases it's a good idea to go to leather conditioner designed more for leather jackets and shoes. The reason that these latter ones aren't the first pick is that they can stain clothing - but in the case of worn leather, pretty well all the conditioner will be completely absorbed and so none will be left to stain any clothes, anyway. (Note that these 'strong' conditioners can also darken the colour of the leather - fine on blacks and browns but not so good on cream leather.)
Apply the conditioner to a clean damp rag and wipe over the leather, one panel at a time. A clean paintbrush can be used to apply the conditioner in tight spots. The cream should be applied quite lavishly and left for a few minutes, before being wiped over again. (If you apply it sparingly in the first instance it doesn't get a chance to be absorbed.) If the leather is badly worn, the conditioner may need to be applied with a small sponge.
On perforated leather, apply the conditioner to the cloth or sponge - rather than the leather itself - before wiping the leather. This will prevent a lot of the conditioner disappearing straight into the interior of the seat.
Be patient during the conditioning process. This is not like spraying vinyl with Armor-All, where a glossy shine is the immediate reward. A car with good condition leather will still take a few hours to have its interior cleaned and conditioned, while a car with worn leather may need three or even four treatments, spaced a day or so apart. Beware of the initial flush of enthusiasm - most old leather looks a heap better after just the first application of conditioner... but a day later when all the conditioner has been absorbed, it can look pretty much as it did before! That's the clue that you need to do the process again... and again.
Once the leather has been fully treated, you may be concerned that it looks dull. However, buffing with (another) soft, lint-free cloth will bring back the shine. Following restoration, further treatments will be needed every 3-6 months, depending primarily on how much sun the interior is exposed to.
The black leather (apparently it's actually buffalo hide) in this 1985 BMW 735i didn't have any tears or really bad scratches, but it looked very faded and had colour variations through it.
The best restorative proved to be Renapur Leather Balsam which contains beeswax and jojoba oil. It's applied with a small sponge and goes a long way - just as well, as some parts of the interior required three treatments. However, the difference that it made was extraordinary.
Here's the side of the centre console before (it's worth clicking on the pic to enlarge it)...
...and here it is after treatment. The dry whitish appearance of the leather has been replaced by a rich, lustrous black.
If you're looking at buying a used car with leather, keep in mind that even if the interior looks quite shabby, so long as there aren't tears and the leather hasn't gone completely hard and brittle, it's possible to make it look a million times better at very little cost. And even if it's badly faded, leather dyes are available to bring it back up to condition.