A review just posted from Petrol Ped who is a long term owner of various petrol S4 Avant. Just posted. Interesting to see what he thinks, and whether he makes any of the points I made in my review (yet to watch). I test drove the following vehicles back-to-back to see which I liked the best Audi S4 Avant (2018) 6 cylinder 3.0L petrol (354 PS) petrol model - CO2 emissions combined (National V) of 175g/km with combined cycle 7.7l/100 km 0-60 in 4.9 secs Audi S4 Avant (2019) turbocharged diesel V6 with 48V mild-hybrid, -CO2 emissions combined 166 g/km with combined cycle of 44.8 (NECD) 0-60 in 4.9 secs The diesel also has a system called AdBlue which is a liquid solution of urea (the stuff found in urine), and when it meets a hot exhaust system it releases ammonia which is a catalyst to a chemical reaction that converts dangerous Nitrogen Oxides into two harmless products – water vapour and Nitrogen I drove the petrol first, then the diesel Engine Sounds The petrol was very smooth, with a classic petrol rev sounds. The diesel was a more grunty/grainy sound. I understand it is acoustically enhanced. Not as nice as the petrol but perfectly fine. Handling and Performance Both cars handled very similarly, were both 4 wheel drive and felt fast. The petrol somehow felt faster at the same speeds as the diesel which seemed to reach higher speeds with less fuss and you had to keep a close eye on the speedometer to ensure you did not go over the limit. The performance felt the same. I did not notice any turbo lag from the diesel (apparently addressed by the mild hybrid system). Technology Both had Virtual Cockpits. The 2019 car had a newer system that looked a little more clear (with slightly larger central screen with touch) whereas the 2018 car had a MMI system. In the news car the VC looked sharper and had driving tip pop ups with I liked Which car did I like best? From a pure driving experience/sound experience I liked the 2018 petrol car better Which car would I buy? Taking a real world view, and thinking about emissions, cost of motoring, and given the similarities of the cars performance I would go for the diesel, on the basis it handled the same, would ultimately have lower emissions and running costs, and be a year newer, taking into account when financed, due to lower APR on a new diesel car the costs were not that different for the buyer for a 1 year old petrol, despite the diesel being ~£10k more if bought outright. If finances were less of an issue I would go for a Audi RS4 Avant when the new model comes out My conclusion Audi have done a great job with new diesel S4. Purists (petrolheads) probably won't like it as much as the petrol version but it's almost as good, and as a practical car it is a better option.