Everyone will have a worry that they may not be able to make their repayments and what might happen then. You should do everything that you can to pay back the loan. As soon as you realise that you will not have enough money to make a repayment, then telephone them. Try to negotiate smaller repayments and explain your situation. It is likely that they will do what they can to help. Make sure you talk to them though as just skipping payments could have bad consequences.
If you cannot make the full repayment each month, you will find there will be charges. Loans will vary in how they work but there is likely to be a late payment charge, other fees or an increase in interest. If you negotiate a lower repayment plan you could find that it is a lot more expensive than what you organised originally.
If you do not keep up repayments then your vehicle could be repossessed. They can take it away and sell it to get back the money that is owed. They may prefer to renegotiate with you with regards to payments as this could make more money for them. However, there is still a risk of bailiffs taking your vehicle.
There is a risk with all loans with regards to charges going up. All lenders have charges for late repayments and things like this but you will find that an unsecured lender is likely to charge more because they are taking on more risky customers. It is worth finding out what their charges are before you take out a loan and think about how you will manage to make the repayments.
It can be easy to focus on the present and think about how the loan will help you now, but you need to consider the future as well and how it will affect you then and how you will manage to pay it back. Think about how you will manage if the vehicle is taken because you have not been able to pay back the loan and also how you will manage repayments if you have another unexpected expense or lose your job.