HI all hope that this is of interest! I currently own a Merc E350CDI but was attracted by the performance of the CLA - being sensible(!) I thought that I ought to look at all alternatives and hence found the S4. I test drove the S4 first and found it an almost ideal mix of performance, space, quality and cost. It was very responsive (supercharged) growled when pushed and quietly got on with cruising at 70ish. In contrast the CLA was dissapointing it probably had better performance but with a noticeable delay in throttle response, the finish was in a lower class and the engine drone at cruising speed awfull. If you want a bit of a weekend hooligan go for the cla - maybe but for everyday fun and use the S4 is in a different class and considerably cheaper (cheap being relative!!). I just have to wait 3 months for mine to be delivered!!