Motorways and Autovias - 120 km/h (72 mph)
Standard roads - 100 km/h (62 mph)
(meeting at least one of the following criteria)
one-way roads
roads with more than two lanes for at least one direction of traffic
roads with shoulders more than 1.5m wide
Other standard roads - 90 km/h (55 mph)
Built-up areas - 50 km/h (32 mph)
Residential areas - 25 km/h (15mph)

Muliply the kilometers by 6 and move the decimal point 1 place to the left:
8 kilometers = 4.8 miles
12 kilometers = 7.2 miles
Speed limit 70 = 42 miles per hour

On standard roads (but not motorways or autovías), cars and motorbikes are allowed to overtake at 20 km/h over the standard limit, if the vehicle being overtaken is travelling below the speed limit, and there is no posted speed limit lower than the standard. This permission decreases the time needed to overtake, and increases safety in the process.

On motorways, a minimum speed of 60 km/h (37 mph) is mandatory for all kinds of vehicles. Minimum speeds in the rest of roads are one half of the generic speed limit for every vehicle. If a posted speed limit sign is below this value, the minimum speed is the posted limit minus 10 km/h.

No legal sanction is established for driving within 10 percent over the speed limit, depending on the specific limit of the area.