Alan,
I've sprayed, brushed and "wiped' leather dye on various German leathers. IF I'm doing a complete seat (or panel), I've had the best success with the 'wiping' method (similar to wiping stain on a piece of wood). I use several (maybe 6-10) thin applications, allowing at least 1-2 days between applications.
I've also been using a procedure I got from a Ferrari Forum to prepare the leather surface. First, I wipe it with a clean cloth soaked with lacquer thinner to remove all the old dead 'paint'. I keep doing this until essentially no more color is released from the leather onto the cloth. Then, I use several treatments of a leather softener (I've used many, I like ColorPlus Soffener, or Leather Therapy), allowing at least 24 hours between applications (until no more seems to sink in during that period of time. Then, another wipe or two with a fresh cloth soaked in lacquer thinner to remove any softener on the surface, let dry a day or two, then apply the actual coats of dye. Yes, a long, involved process, but I've found it provides a very durable dyed surface and quite supple long lasting leather.
Just my procedure - if you are interested in considering it.
Gary