The link that Sigcurious provided is a RECOMENDATION
and it's not an accurate reflection of the law.
The pamphlet "Illinois Gun Laws, Common Questions & Answers
Illinois Gun Statutes" states:
it is recommended that, in order to be in compliance with all statutes, all firearms be transported:
1. Unloaded and,
2. Enclosed in a case, and
3. By persons who have a valid FOID card.
The actual statute says:
does not apply to or affect transportation of weapons that meet one of the following conditions:
(i) are broken down in a non-functioning state; or
(ii) are not immediately accessible; or
(iii) are unloaded and enclosed in a case, firearm carrying box, shipping box, or other container by a person who has been issued a currently valid Firearm Owner's Identification Card.
The Illinois Supreme Court ruled on 10/8/2009 Docket # 106367 that the Center Console of a vehicle was a case and a firearm could be carried in the closed Center Console.
People v. Holmes, Ill. Supreme Court, Docket # 109130, Opinion filed 4/7/11.
The defendant owner/driver of a motor vehicle, an Indiana resident who had been issued a carry license by his home state, was stopped by Chicago police officers for a traffic violation. Pursuant to a search, a 9 mm handgun was recovered from a backseat armrest of the car. The Court noted that “[t]he armrest separated the two back seats and contained a storage compartment that closed with a latch. The compartment could be folded up into the seat or left in a down position.
Illinois State Supreme Court found for the defendant in this case.