The first way to save time is to bundle your trips to a similar area. For example, you have to go to the grocery store on Saturday, and you also want to meet up with a couple friends on separate occasions. One lives near the grocery store, and the other lives in another part of town. If you had the choice, schedule to meet the friend that lives near the grocery store right before or after your grocery stop trip. That way, you save the time of making two separate trips: getting prepared to leave the house, and the time to drive there and back.
If getting prepared to leave the house takes you 20 minutes and driving takes you 20 minutes, to and fro means 40 minutes. Altogether, you save an hour if you bundle your two trips (grocery store and meeting friend that lives near grocery store).
I use this trip bundling strategy often. If I have to go downtown to meet someone, I try to book another meeting with someone else on the same trip. It takes me about 30 minutes one way to get downtown, on top of getting prepared to leave the house. By bundling multiple meetings, I save over an hour than if I make two trips at two different times to meet two different people.
Using this method, you can save at least 1 hour a week.