If you are looking for a travel wall charger, the amazon 2 amp 10 watt chargers are solid, reliable, efficient, small, and output a strong 10 watts of power. There are a few adapters you can buy for a few dollars that let you plug into other countries as well.
As for a car charger, you can get them for like $5 on amazon that output at least 1 watt. There is also a kickstarter I saw that is a really cool take on this, as well. It is like a USB to Lighter adapter, except that when you unplug it, in continues to charge your phone by using a built in lithium battery. When you plug it back in your car, it recharges. It has LED lights and it's pretty cool, I am looking forward to it's launch.
It is called the pocket rocket, and you can find it on facebook at facebok.com/pocketrocketpower or pocketrocketpower.com
Also, please note that the Nexus 6P does not have a QuickCharge standard. It is using the completely standard USBC 2.0 connector. This is still a 1.5 or 3 amp 7.5 or 15 watt charge standard, which is pretty darn fast. This means you don't need to find one that is "Quickcharge" compatible, any 2amp to 3amp USB adapter should work fine.