Do you actually have a guaranteed reservation for a 2014 Dodge Avenger?
Or do you have a reservation for a "Dodge Avenger or similar," with your rental car company able to assign any car in that car class (probably intermediate/midsize)?
Putting luggage for 5 people in the trunk of any midsize and closing the trunk will be challenge. Of course, that depends on the sizes of the bags.
According to
Budget, a Dodge Avenger can hold 3 small bags, 2 medium bags, and 1 large bag. That being said, such information from a rental car company is only useful for comparing cars, not to know if
your particular luggage will fit in a particular car. See
http://www.budget.com/budgetWeb/html/en/cars/medium.html
"The 2014 Dodge Avengers trunk has 13.5 cubic feet of cargo space, which is smaller than most other midsize sedans trunks." See
http://usnews.rankingsandreviews.com/cars-trucks/Dodge_Avenger/Interior/
Let's compare that to a Ford Taurus, a large car usually considered premium by rental car companies. According to US News, "With its split-folding rear seats and 20.1 cubic feet of cargo space, the 2014 Ford Taurus has one of the largest trunks among affordable large cars."
With five people, you would be better off with a larger SUV or minivan, or at least a fullsize car.