I agree on the 2013 car being a very good club race car on our indoor asphalt track, had the most fun in RC in several years with it. Worked well at TITC also.
Was disappointed with the out of the box performance of the 14 and skipped the 15 since it seemed so similar. Have a 16 now and after struggling looking for a good setup am finally happy with it.
Still regret selling my 13 though...