Are they responsible for getting me another car or should I sue if one week after purchase, my car burned down on the interstate?

Definitely make a claim with the car manufacturer and dealer. You also may have a case against the insurance company.

Get a lawyer and let him review all your documents and advised you.

Get a lawyer. You may have a choice; sue your auto insurance company or sue the manufacturer. Your lawyer will explain to you which is preferable.

Contact the manufacturer then.

This depends on who "they" are, what type insurance was involved in the denied claim, and what cause the fire. I will make some assumptions. I will assume your own auto insurance denied the claim because you had no collision or comprehensive coverage. If you did have comprehensive coverage, you may want to challenge the denial of this claim. I will also assume the fire was caused by the defect mentioned in the recall letter. If it was caused by such a defect, the manufacturer may be liable. If you purchased the vehicle new, the manufacturer would almost certainly be liable because the vehicle should still be under warranty. In this is the case, you should contact the dealership about filing a claim. If it is a used vehicle, but still under warranty, same thing. If it is used and the warranty has expired, it is not as clear. Then, rather than a breach of warranty claim, you would have a product liability claim based on a defective product. Often, this claim is made in personal injury cases, but could be made in this case for your property damage. You should probably contact the dealership or manufacturer in that case about a claim.