Here is some useful information about Road types and speed limits in Spain. Read more here.
Autopista (motorway) – A or E – prefix to road number: these can be toll roads (peajes). Maximum speed 120 kph (73 mph)… example, AP7 or E90
Autovia – dual carriageway, not necessarily with a central reservation. Speed limits vary from 60 to 120kph …. example A8
Carretera Local – highway. Speeds are as signed, but usually not more than 90-100 kph
Carretera Nacional – N or CN – prefix to road number, main roads. 100 to 60 kph …. example CN322
Speed limit for towns it’s 50kph.
Local small roads are often CV roads
Please note that the speeds are somewhat less for various classes of vehicles including towed trailers/caravans.