If you were to crawl under the hood to do like operations in both cars, like say change starters, you would come away with a distinct dislike for repair and maintenance of the 300D vs. the 240D. Even though these two cars are the same except for one extra cylinder, working on the 240D is like working on a Model A while the five cylinder is a huge PITA.

As long as you don't have to do your own work, you'll enjoy the 300 just fine as compared to the 240. The difference the extra cylinder makes in these two cars from a repair and maintenance standpoint is staggering.

Have a great day,