Sunday driver is a term used to describe leisurely drivers who take their time on the road and often cause frustration for other drivers in a hurry. Some synonyms for Sunday driver include slowpoke, dawdler, snail-like, leisurely, unhurried, etc. These terms all suggest a relaxed pace and lack of urgency. Other phrases that convey similar meanings include crawl, plodding along, ambling, and sauntering. It's important to note that not all drivers who take their time on the road are Sunday drivers; some may be cautious or inexperienced. However, if you want to convey a sense of leisurely driving, these synonyms are a good place to start.