There are a large number of people who take an interest in antique cars.  They are usually well off and can afford to pay a good price to keep their favorite toy in working condition.

You can also do good business by renting or leasing antique cars.  The movie industry is one area that would be your customer.  Other potential customers can be found in the wedding industry, marketing industry, nostalgic individuals, etc.

Antique car sales is a growing segment of the automobile industry.  People who want these type of vehicles are willing to pay a premium to obtain their antique cars.  You can buy these vehicles from the bone yard and rebuild and sell them. 

The big auto makers are no the only ones that can export vehicles for sale overseas.  This is an expanding market as countries in Asia, Africa, Central America and South America join the global economy.  Many of these countries offer import opportunities for small businesses because they are not served by the big auto makers.  You can work with an importer in those countries to develop a lucrative business.

Dealerships do not have a monopoly on new parts.  With a little research on the web you will find businesses that sell the same new parts at a much lower price than what the dealerships sell them for.  You can find an overseas source for new parts at very low prices, then turn around and sell them in the States at a lower cost than what the dealerships charge while still making a decent profit.

Dealerships do not sell used auto parts.  To get used auto parts you have to buy them from a junk yard who take the parts off of damaged automobiles that are beyond repair.  They removed the individual parts that are not damaged and resell them.  This is a very lucrative business but requires a large yard and an extensive logistical operation to get the damaged cars and remove the individual parts and prepare them for resale.

To sell new automobiles you have to have a dealer relationship with the respective auto makers.  This will require a substantial financial investment.  If you can afford it go for it.

Not everyone wants to buy a new automobile.  The market for used automobiles is huge.  Used car sales involves buying used cars at a very low price, fixing them up and offering them for sale at a reasonable price and making a decent profit.  You will need a shop to perform maintenance and a large area to store and stage the cars for sale. 

You've heard of the big auto rentals such as Enterprise, Hertz, Alamo, etc., and you probably think that there is no room for another one.  Well, you're wrong.  There are lots of other auto rental companies that you're not aware of and they do very well.  They do so because they offer the same service but at a low price and they serve areas that are not adequately served by the big rental companies.  You can do well by starting your own auto rental company.

Accidents happen every day.  There is plenty of body work to go around.  With a little training you can acquire the skills to start your own body shop and make good money.  You will need a facility to work out of and the tools and materials to apply the trade.

A car wash in the right location can be a very lucrative business which requires the least amount of skills.  With a facility, water, soap, wax, rags, vacuum and other cleaning materials and you're in business.

Auto electronic repair can specialize in repairing and installing car stereo, alarm/anti-theft systems and troubleshoot and repair auto electrical systems.  This will require specialized skills in electronics.

You can offer general maintenance by doing basic repairs such as brake change, tire repair/replacement, radiator fixes, hose replacements, alignment, etc.  You will obviously need a location to conduct the business as well as all of the special tools and equipment.

With some basic training and you start your own glass repair business.  The technology evolved over time to make this an easy task.  You can develop a business around onsite repairs where you send out a repair team to the customer rather than having the customer come to you.

Every car has a muffler and sooner or later they have to be.  All you need is a place with lifts where you can raise cars and change their mufflers.  You don't have to do anything else. Make that your specialty.

Car pimping is becoming a lucrative business.  Pimping involves making changes to the vehicle style based on the owner's request.  Changes could include paint styling, adding lighting to various parts of the vehicle, adding electronic equipment, etc.  This requires some skill and creativity.

Oil change change places are becoming very popular businesses.  A business that specialize in only changing oil on vehicles of all types.  This is a very simple and straight forward task.  you will need a garage with lifts or pits some basic tools and the required oils.

The cost for accessories from dealerships are ridiculously  high.  You can obtain accessories from overseas sources at rather low prices and sell them for far less than what the dealerships are selling them for and still make a decent profit.  Placing the business close to the customer and offering sales over the internet will help to generate large client base.