This is a crossroads moment and you have to be very clever about what you want to achieve.
As far as the Car Brand field is concerned, provide a combo-box for fields where exact information is necessary or the dropdown is too big. The Car Brand field fits perfectly in this category.
Now, let's talk about making a lengthy or detailed form feel easy to fill.
The key here is to break it down into logical categories and make each header a step like:
Personal info (given that you're working on a hitchhiking app, you want people to be verified and be anonymous at the same time). Ask for the name and age or maybe use FB, Twitter, G Plus to verify them but promise to (and actually do) keep the details secret. Just take the bare minimum.
Car info - Like brand and name or keep it simple and just ask them the number of seats because that is the only important requirement here
Details that are pertinent like personal car ethics, rules, etc.
Another way to keep the user engaged for a longer time is to have avatars or characters on the page. Not conventional, but it works. Take Google Now's weather card as an example. The frog does make the info more interesting
Hope this helps