You've done all the planning and spending, and you're finally embarking on a much-needed family vacation. You've even reserved a rental car with a car seat for baby, so that you don't have to lug yours. So smart! Unless it's not, of course.

While rental car companies offer infant and toddler car seats as an "added convenience" (and at an additional charge, of course), it turns out that the reality may be worse than you could've possibly imagined.

Debbie at DeliciousBaby chronicles the story of Advantage Rent a Car's failure to provide adequate car safety seats even after an ABC expose and new standards had supposedly been enacted. But it gets even worse than that:

Shocked to hear another story of blatant disregard for basic safety and California State Law, I flew down to Los Angeles to see for myself. Los Angeles International Airport is one of the world's busiest airports, and when I arrived, the agency was crowded with customers. Many were families with young children headed to Disneyland or Los Angeles beaches. Curious about the condition of the car seats, I asked to rent both an infant seat and a toddler seat. What I found was shocking and upsetting, especially after the company's strong promises about cleanliness and safety.

The first toddler seat I was given had been bagged as if it had been cleaned, but it was visibly soiled and covered in crumbs. I returned it to the agent, who agreed that it was filthy, and handed me another (bagged) car seat. When I opened the bag, I smelled a strong stench of vomit. The pictures I took show that the seat was visibly soiled too. Neither toddler seat had a manual or the "locking clip" that would be needed to install it in some cars.

This story left me at a complete loss for words. To say that this scenario is horrifying seems like an understatement. Surely this is something limited to a single airport, or at least to a single car rental agency... right?

Unfortunately, the words may change, but the melody seems to be the same in plenty of situations. It turns out that car rental companies are just not all that concerned about giving you a clean, safe car seat for your child. Which would be excusable, I suppose, if we weren't talking about the safety of a minor.

I guess this is truly one of those "if you want it done right, you have to do it yourself" sorts of things.

Mary Jo at Mama's Gootiful Baby agrees that you should bring your own, after her experience with Dollar Rent a Car:

The car seat was a COSCO (here's a list of all the COSCO car seat recalls in the last 14 years) and looked like it had been through 16 food fights, 11 cross-country vacations, and, at least, 2 world wars. I said to the man who'd "helped" us, "This looks really old...Do you have any others?"

A FEMALE employee down the counter piped up right away and said, "They're all less than a year old."

I turned the car seat sideways on the counter and found the manufacturer's date. "Um. It says 2005?"

She ignored me. I demanded a new carseat. I got a new one. Manufacturer's date: 2006. Better, but, you know, not less than a year old. Anyway, I lugged it out to our rental vehicle.

For the next HOUR, Tim tried to install this piece of garbage in our our vehicle, without a manual (not provided by Dollar).

And SkylarKD at life as I know it... had her own run-in with Hertz:

We reserved our infant seat weeks ahead of time, and when we picked up the rental, we were given a car seat to install ourselves. The employee wouldn't install it for us, and she didn't have an instruction manual. My husband mentioned to the clerk that their website said that the seat would be installed by trained personnel. She said that she had taken the course for installation but said she wanted nothing to do with it. She said that she didn't want to end up in court if we got in an accident!

She (and Hertz corporate, when we later contacted them) said that they would be changing the website information shortly, but they still haven't changed their policies.

And even worse than all of that, the seat was FILTHY. I've never seen a car seat so dirty. There was rust all over the bottom of the seat and some in the car base as well. Who knows how damaged it was! We didn't feel safe using the seat for our baby, so we asked for a replacement, and were told that there were no other car seats. The employee also refused to call another location to reserve a seat for us to pick up.

I don't know if these existed back when my kids were tiny, but SkylarKD recommends a Radian folding car seat for traveling, for ease of transport. It folds flat, which is unlike any other 5-point harness seat I've ever seen.

Of course, unless you're bringing your own car seat onto the plane with you, you may still find yourself in a bind, as Vanessa's family did on a recent trip:

We were exhausted after more than 15 hours of traveling. We dragged ourselves off of the plane and over to the luggage pickup. We got our two bags. And waited. And waited. And waited... but no car seat. Turns out they lost it. Lovely. Stranded a million miles from home at 1 AM with no car seat. Fortunately, they loaned us a really nasty pet-hair covered seat until they could find ours.

If you still want to risk renting a car seat, DeliciousBaby also has a great piece on Safety Tips for Renting a Carseat, but let's be realistic, here. You've just traveled however many hours, with a baby or toddler; do you want to start documenting the unsuitability of the rental car seat while your kid screams his head off, or do you just want to get where you're going? Right.

Bring your own car seat. Bring it onto the plane with you -- that's the safest way for your child to ride on the plane, anyway, and most popular car seats are FAA approved. While I agree that you ought to be able to rent a suitable seat from a rental car agency, it's simply not worth the gamble.

BlogHer Contributing Editor Mir also blogs about issues parental and otherwise at Woulda Coulda Shoulda, and about the joys of mindful retail therapy at Want Not.