Rental Options Image You've scored a great deal on your car rental by checking discount codes and diligently comparing rates. Don't pat yourself on the back just yet though. As many people find out at the rental counter, that may be only half the battle.

Are you traveling with small children? If so, you may need one or more car seats to keep them secure. Not familiar with the local area? A GPS navigation system might be important. These add-ons may add extra charges to your rental. In some cases, these charges may even end up costing more than the time and mileage charges for the rental itself.

Here are a few strategies to avoid or minimize the cost of rental options:

Child Seats

All the major rental companies offer child seats for rent at their locations. It's a great source of revenue for them, because they can rent a $60 child seat hundreds and hundreds of times for $10-$15 per day. It doesn't take a math whiz to figure out that this is a high margin item for them.

There is one secret weapon in avoiding the charge however. Most people don't know that AAA members get one free car seat when renting from Hertz. Hertz is the only company that currently works with AAA, and you must book using the AAA discount code 1805452. (You can enter in discount codes right on the AutoSlash homepage.) On a one week rental, this can add up to over $80 in savings. Even if the Hertz rate is higher than other companies (AAA discount code can bring the cost down significantly), the savings on the car seat alone may more than make up for the difference.

The other strategy is to bring your car seat with you. While it can be a pain to lug it through the airport, you will save on the rental cost, plus you'll avoid potentially getting a dirty or worn seat that has seen better days.

GPS Navigation Systems

Paper maps are quickly becoming a thing of the past for many people. The convenience and efficiency of GPS-based navigation systems make them a compelling add-on when traveling in unfamiliar areas. The rental companies are more than happy to cater to their customer base by offering portable units for rental. Costs range from $9 to $15 per rental day.

In some cases you can find coupons on the rental company websites that will offer a free day or two of GPS rental. If you're a member of BJ's or Costco, you can often find coupons there as well. Currently Costco is showing an offer for Budget which gets you up to 30% off, a free GPS Rental and $30 off your rental on top of that. Not too shabby. They offer a similar deal for Avis, but instead of free, the GPS cost is $2.99/day.

Another option is to buy a portable GPS unit and carry it with you. They can be found on sites like Amazon less than $80. They're small enough to fit into a carry-on bag, and you get the benefit of being able to use it in your own vehicle as well back home.

Lastly, if you own a smartphone like an iPhone or Android, your phone can be a GPS. That means that you can run an app that gives you turn-by-turn directions and voice guidance features. There are free built-in apps like Apple Maps and Google Maps that work quite well (as long as you have a cell signal) as well as paid GPS apps offered by Garmin or Tomtom that work anywhere, even in rural areas without phone coverage. This is a great way to avoid the cost completely from the rental company.

Always Negotiate

You can also sometimes negotiate at the counter for a discounted rate or to waive the fee entirely. Your chances of succeeding go up considerably if you're taking another add-on. For example, if you're planning on taking the additional insurance offered by the car rental company and you'd like GPS as well, see if they'll throw in the GPS for free or give you a discount if you take the insurance. Most rental agents work on commission, so they're often willing to sweeten the deal if you'll take one or more add-on items. If you don't ask, you don't get.

Be Strategic

The key to getting a good deal when options are involved is to think about your rental strategically. Calculate the total cost with options when comparing rates across companies. If you save $20 on the base rental cost with Company A, but end up paying $50 in options where you could have gotten that option included with Company B, you've actually lost money. You don't want to be penny wise and pound foolish.

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