Advertising uses the basic principles of psychology to influence the customers Mind. Every advertisements are made in a unique way to influence their customers to notice their advertisements and lean towards them in decision making process.
The basic psychological aspects of the advertisements are

1. Emotion
2. Persuasion or authority
3. Memory
4. Colour

Car advertisements or wrap advertisements uses all these basic psychological aspects to influence your customers.

Emotion
Fear, Love, Pleasure, and vanity are the main emotions a person can have, fear being the most powerful emotion.
You can use all these emotions in a car advertisement.

Fear 
Fear of losing out an offer pushes your customers to buy your product or services.
20% discount or “only these many left” will create a uncomfortable situation for customers and the customer will end up buying your goods and services.You can use “fear of loosing out”  sentence in your ad on car to attract more and more customers to user store.

Love 
Giving loved once the thing that they desire is a strong emotion. You can leverage these emotions by placing a banner advertisement on the car with picture of two relationships.
It can be Family, friends, Husband &  wife, Father-Son,Mother-Son, Mother-Daughter..Etc

Pleasure
Joyfulness is contiguous, When your customers sees people having fun they imagine themselves having that fun with their friends or family, This gives you chance to influence your customer with joyful car advertisements.

Vanity
People always like the sense of well being and relevance, They want to stay close to the current trends. You can use these “latest trend” or “You don’t wanna miss this” statements on your car advertisement to highlight your company and attract more customers.

Persuasion or authority
People follow celebrities, if a product or a service is used by a celebrity your customers tend to follow them too and end up using your product or the service.You can use a celebrity photo (with consent ) on the car advertisement influencing your customers to buy your product or service.
When people with right knowledge “So called experts” say to use your product people tend to lean towards your company product or the service.You can use pictures of doctors, scientists  on your car advertisement.

Memory
Human memory is very tricky thing you can alter the memories just like the Inception movie concept but less action more motion on cars.Memory is not always clear unless people sit and study and struggle to keep it in mind. In normal cases you can alter their memory. This technique can be used for re branding or expanding your market.
Horlicks is generally associated with kids. Horlicks used a branding technique to make their product relevant to adults as well.
You can use car advertising for re branding purposes as well.

Colour
Colour of your advertisement will convey a message to your customers.In a car advertisement you can use specific colour as background to highlight your intentions.Different colours give different meaning.
Red – Passion, Energy, Strength, Intensity, Excitement.
Blue – Depth,Stability,Wisdom,Trust,Confidence
Yellow – Energy,Happy,Attension,Joy
You can use all these techniques for car advertising and attract more and more customers towards your company.