DI is in theory a have your cake and eat it too technology...but issues are still being found as it is still relatively new. VAG being one of the first to mass implement it on most of their cars, and its owners are the first to find some issue with it, with carbon build up being the main issue. IMO that is being blown out of proportion more than it really is, but it is no doubt an issue...And then there is emission, with Gasoline DI being found to have issue that was associated with Diesel probably more than a decade ago, since going DI changes how the combustion process happens especially in partial load condition, more particulate emission becomes an issue. Which could change how emission regulation will be written and expensive exhaust treatment like particulate filter to be use on gasoline car also(something that used to be a diesel thing)....
But as said the technology is new. Toyota's implementation that mixes port injection at part load with direct injection at full load is pretty novel, and I think VAG is going down the same route...
University of Toronto Formula SAE Alumni 2003-2007
Formula Student Championship 2003, 2005, 2006
www.fsae.utoronto.ca