In reply to Dazzle: Cuba is much bigger than you think, its roughly the size of the UK and getting around isn't that easy, at least it wasn't when we were there 6 years ago but we had our bikes with us to get around when we got to our destination.
Its just a tip. They will tell you they can't get you a car unless you pay extra 'admin' fees and then charge about $70 a day for a very ordinary car. Its up to you, thats all.
Having said that Cuba is awonderful place and the people are fantastic, scenery beautiful and you can get good food at reasonable prices ie. lobster for $10-15.
Have fun.