To use the Sleepypod ClickIt Sport or ClickIt Terrain you only need a seat belt - which threads easily behind the dog's back. If your dog tries to spin and get caught up in the seat belt, you'll want to try using the S-clip that Sleepypod offers as an accessory. These harnesses are available in sizes for dogs as small as 20 pounds and as big as 90 pounds.
All Sleepypod carriers are CPS Certified - this includes the Sleepypod Mobile Pet Bed, Atom, and Air. If space is tight in your back seat - for example the carrier is going next to a person or a car seat - choose the Atom or Air. The Atom & Air can also be used on an aircraft. Carriers are best for cats, and small dogs (typically under 18 pounds).
Click here to read more about the crash testing that CPS did of carriers - including the results.
The Gunner Kennels G1 Intermediate with 8’ Tie Down Straps for dogs up to 75 pounds was the "hands-down top performing crate" of CPS's 2015 study. Using the strength rated connection straps (sourced from Gunner Kennels) the product withstood the significant forces generated in the CPS testing as well as other rigorous testing.
Here's what CPS had to say about the Gunner Kennel:
The Gunner Kennel is unique. It has a dual locking feature on the door that provides significant structural support to the door in the case of an accident. With the strength rated anchor straps tightened, the Gunner Kennel’s rubber feet gripped the carpet, unlike any other crate we have tested. This is a significant travel device, with outstanding structural integrity.
Click here to see the full testing results for all of the crates that CPS tested in 2015.