Legal Question in Civil Litigation in California

The limit for small claims cases is $10,000, not $5,000. (The limit was increased from $7,500 on January 1, 2012. Note that lower limits apply in some situations.) But it's not clear to me that you have a viable claim against the towing company.

You haven't told us why your truck was impounded, and you haven't said whether you tried to pay the fees and get it back. If you were parked illegally and the towing company is charging lawful fees for removing and storing it, then you have to pay. If you don't pay, then the company is entitled to put a lien on the truck and then to sell it.

I suggest consulting the details with a lawyer to find out what options you may have.

What makes you think you have a claim against them?

If you could prove they 'illegally' towed and impounded it on their own without authority of police or property owner [parking lot or driveway disputes], yes.

If they simply took in a police tow, you have no claim unless they improperly refuse to release it after accepting your payment.

To retrieve a vehicle from storage you must pay in cash the full tow and storage charges demanded [they are not negotiable just because you think they are high], and present proof of ownership including valid Registration and Drivers License. They also won't release it if there are any title liens for parking tickets or DMV registration violations, until you clear those and present that proof as well. The longer you wait, the higher the storage fees.

Yes, they can issue a lien on the vehicle title until they are paid, or the vehicle is sold by them at auction. The lien prevents you from fraudulently selling the vehicle to some slow-dozer at a 'bargain' price.

After all that, if you can prove their withholding release is a legal violation after you've complied with the rules, feel free to file small claims lawsuit.