Aggregation sites are an excellent place to get started. This will give you an idea of where the value might be in a specific market at a particular time.
Economy cars are the lowest rate available in a car rental. Unfortunately, they are also the most likely to be completely booked.
Often SUVs are the most expensive option for the same relative specs. For instance, many SUVs might be the same size as a mid-sized sedan or a full-sized vehicle.
The airport location can charge anything from a few extra dollars per day to low double digits. These differences can add up on an extended reservation.
Costco membership is one of the most accessible group rates to be a part of because Costco membership has so many other benefits.