Cuban roads being what they are and tourists being what they are, the main aim of the tour group is probably cheap to buy and simple to repair. Everything works in Cuba, just not perhaps up to the standards we expect. When it doesn't work, they stop using it.
Love the country and it's people. The rental machinery is always interesting and unless you get the vehicle with under 10k on it, the shocks will be shot due to being driven by tourists who have yet to adjust to roads in random levels of repair.
The last rental was an interesting almost new Chinese sedan - very well equipped, modest finish and a little crude in handling, overall pretty tight - basically a 2013 package with 1998 execution. I always try and rent something novel when I'm there. It's not about reaching the top of the mountain, it's the journey.
Cheers,
John M.