2008 R8 R-Tronic
100% this. Do not spray water directly into the engine gay. Water will pool on top of the transmission and will rust the guide bolts and transmission mounts.not spraying water directly into the engine bay but just using damp (soap and water) microfiber clothes and drying the same way. Letting water enter and stand on parts in the engine bay (especially the side mesh panels that sit under the vents) will cause rust.
Ask me how I know....
So I'm in the middle of converting my R-Tronic to Gated, and noticed how bad the rust was on my transmission mount bolts along with the associated washers on these mounts: Some surface rust is reasonable given the age of this car (14 years), however the amount of rust seems excessive to me...