OMG I'm so glad Jasper is alright. And hugs to you too, I shake for quite a time after a scare like that!

I use the Guardian Gear harness, it clips into the seat belt snap so it is easy to do and undo. You can leave the harness on for walking.

Here is a link, I got mine from Pet Edge. They also offer other types, but this works for me and 2 bichons. They can lie down or sit up.

http://grooming.petedge.com/catalog/...=car%20harness