Mr. Davis,
First, please note that this forum is not run by Amtrak. It is a privately owned forum by a single individual that was created for the purpose of allowing people to ask questions about Amtrak and to discuss Amtrak. Therefore I'm sorry to say that we can no more get Amtrak to add another car than you can or anyone else for that matter. We simply don't have that power, nor any connections with Amtrak to make it happen.
Second, Amtrak does not have any extra sleeping cars to add to the train. There are only 50 of the single level sleeping cars in the fleet which is a problem for Amtrak. In fact that's why Amtrak proceeded with a new order of cars last year without even knowing for sure that Congress is going to give them the money to buy the cars. That order will include 15 more single level sleeping cars or Viewliners as they're called.
Not being affiliated with Amtrak we at this point in time have no idea what the disposition of those cars will be when the hopefully arrive next year. It may well be that they will add a second sleeper to the Cardinal, but they also may not. I don't know.
Third, included in that new car order is something called a baggage/dorm car. This car will be half baggage and have rooms for the crew. And therein lies another big problem for the Cardinal. Right now there are no crew cars on any of the east coast single level trains; they were all retired due to age. So the crew occupies rooms in the only sleeping car on the train. That reduces the number of available rooms by at least 3 or 4 unfortunately.
Fourth, even if Amtrak did have extra cars to add or skipped an inspection on one car so as to add it to the train on the day you need it, another problem is that there is no dining car on this train. The only food service car is a combination car, half cafe/half quasi-dining car. This single car would be unable to serve enough meals to feed everyone if there were two sleeping cars. And at present, Amtrak has no extra single level dining cars either. That same order that I mentioned above includes new dining cars. The current dining cars that Amtrak is using on the single level trains are now 60 to 70 years old because Amtrak has never been given the money to replace them.
Which brings us to the subsidies that you mentioned. Consider the following; in the last 3 years the Fed has provided more than $62 Billion in subsidies to our highways. That's more money than Amtrak has received in its entire 40 years! So if you want to write to the local papers or go on the Today show, please be sure to make the point that you can't get a sleeper because Congress isn't providing enough funds for Amtrak to buy enough new equipment.
I do understand your frustration; in fact most of us here do. Even on trains that have 2 or 3 sleepers it is often impossible to get a room during the summer months if you haven't already booked by May. When Amtrak first got the new bi-level Superliner cars 30 years ago, they had 125 sleepers in total. Today after several accidents, they only have 111 sleepers left. Looking at the entire Superliner fleet, they had 479 cars of all styles and are now down to 431, a loss of 48 cars. And again, Congress have never shown any willingness to help Amtrak buy replacements. Thirty years ago in 1980 Amtrak carried 21.2 million passengers, last year they carried 28.7 million. So they're carrying more people with less equipment than ever!
So again, please put the blame where it belongs, on Congress for their failure to fund Amtrak properly!