While saying “I love you,” isn’t necessarily quantifiable, it won't hurt to say it often. Not only will you earn brownie points, but it also is psychologically rewarding for both involved.
There is also the high likelihood you have done something that has gone unnoticed… and then you felt a little upset or even disrespected.
Opening the car door is just one way to show your level of kindness to your wife. Nothing says or makes a quick friendly gesture like opening the car door.
Just like taking care of your health shows your wife your intent, any self-improvement just makes your significant other happy. One way to improve… read in front of her.