Get a driver in Lisbon can be pretty challenging if not booking in advance. Although most drivers can understand and speak some English, to get an English Speaking fluent driver and at the same knowledgeble can be a hard task. When not booking in advance, you end up getting a last minute taxi on the street, which may not be the most convenient and interesting way of visiting Lisbon and surrounding cities.
1) Lisbon Private Tours – http://lisbonprivatetours.com/
This company is one of the leading tour companies in Lisbon, operated by Sintra Magik, leading tour operators around Lisbon, specialized in Private Tours around Lisbon, Sintra and Fatima. All services are provided with luxury transportation and driver/guide.
2) Portugal Luxury Driver – http://portugal-luxury-driver.com/
This website provides luxury transportation with driver (sedan and minivan or minibus). They cover the major cities around Lisbon (Sintra, Fatima, Evora) and also Algarve and northern Portugal (Coimbra, Porto, Douro, Braga). All drivers are English speaking.