No one type of crate is 100% safe when traveling with your dogs, the Airline crates would obstruct my vision in the vehicle I have. I was in a car accident 3 yrs ago while driving my old Outback. I was stopped and waiting to make a turn when I was rear ended by a van going 45 MPH. The hatch of my car popped open and lucky for my old girl she was in her crate (a wire one)and not loose on the highway. Although she did get tossed around in her crate she remained in my vehicle with her crate intact. I have friends who have had both airline and wire crates break from the impact of a crash. What ever type of crate you can fit in your vehicle is better than no crate at all....JMO

I like to use airline crates - 400s and 500s - whenever possible because if there's a mess it stays in and doesn't get all over the van! If not one of them it's usually a 36" crate. When I have a whole lot of dogs to carry, I have some 30" wire crates that I can stack and the smaller/younger dogs are fine in them for a trip.

I have 2 of the Midwest side by side crates(42") that are narrower and fit accross the back of my GMC Yukon XL.....then I have two 36 " double door crates that fit in the back seat area....it takes some adjusting but they fit perfectly....so I can take 4 of my dogs safely and occassionaly a fifth rides shot gun (short trips only).

I was in an accident with my dog in the car. He was in a wire crate that was secured to the next one to it. He didn't have a scratch. I however was not so lucky. That crate actually protected him. I wouldn't use airline crates for anything but shipping on a airline and only then because I have to. I use wire for the excellent air circulation. Airline crates are hot for any animal. If mine make a mess in the wire crate I guess I will just clean it up.

I drive an Envoy and use 2 of the SUV crates. My big boy fits just fine in them.

Thank you everyone for your input.

OK...the original poster was looking for suggestions on crate sizes. They did not ask which was safer, just what they should look for. Being the fact that their top consideration in buying a vehicle that will hold the crates they need vs buying just any vehicle and and not caring if they can crate their dogs or not is wonderful.
They are crating their dogs while they are riding in a vehicle, I think we should stop the arguing and applaud them for that. Accidents happen, airbags, crates, whatever, we never know when or what is going to happen and what will or will not protect us. At least they are trying to keep their dogs safe, and it seems like it is a top priority

Try Central Metal Products 48 x 36 x 28 Mini fold. Plenty big for a Labrador Retriever. Agree with the comments on heat in Airline Crates. I think that Metal is best because you can see the animal. I put small Newfies in these as well and they are very secure latching with a strong spring so no escapees during shows .

Original poster. You asked about the side by side SUV crates. I have one of those. I believe they come in two sizes. I have the smaller one that is 36 inches long/21 inches wide and 26 inches high. I put it next to a traditional 36 long by 24 inch wide and 26 inch high crate to get in the back of my van. My Labs have fit fine in it.. as it is plenty long and that difference of 3 inches of width did not seem to affect them in any way. They also make a larger version that is 42 inches long/ 21 wide and 30" high. In most vehicles it is the width that is the issue.
I do however have fairly small/ moderate Labs .

Kim S.

There are also Central Metal Bench Crates, narrow width. Pricey but strong. The Bench Crates have the tiny squares like the original Kennel Aire did. They also come in an unusual size, only 40 inch long, as well as the 36 x 21 and 42 x 21. They are not prone to flying open in a tipping or roll over accident as the MidWest ones are. They have spring loaded latches. (If you doubt me, just put a MidWest crate on its side: the slidebolts unlatch if the side down is away from the closed position.) My regular mini fold are decades old, and so a friend's bench crates. Unlike the regular mini folds, they are more stable in a vehicle as they are not up on legs. For a yellow Lab, you may wish to special order the stainless steel pans instead of the galvanized ones. OR line with a matching plastic pan from MidWest, if it fits.