We have an 8 wk GSD male puppy and want to get a guard for the car. Which is best tubular or wire mesh?
I would appreciate any comments on this.

Thank you

Personally I would go for a full crate as there is less oportunity for the pup to chew the interior of the car. Failing that the mesh type that bolts in properly. Not the sort that just has pressure and wing nuts to hold it in place. It is going to be a big dog and you need something substantial to protect you both in the event of an accident.

I had the tubular type in car first cars years ago and my mongrel had the horrible habit of putting her head through the gaps and getting it stuck. 
There was nothing I could do while driving, so she would pull so hard to get out that the whole lot came crashing down.  I would never have one again and my new car is all kitted out with full mesh gaurds behind the seats and at the tailgate. 
Barjo do some great guards, have a look at their website.  They also do second hand guards too.