Well, first of all, Fuelly relies on members for all of the data. If someone tells us they have Jetta with an L2 engine, that's great. We don't do any sort of checking. And once someone chooses a particular engine, it's then available for all members that follow.
When you see an L that generally means inline, or the cylinders in a straight line. As opposed to a V, which means that cylinders are in a V-shape.
Just figure that the number corresponds to the number of cylinders. Our system uses the notation L4 and L5 for Inline-four and Straight-five. Once you get higher than five cylinders, you're probably dealing with a V6 or V8.
If you see an H, that means it's a hybrid engine. And there are some other odd engines in there honestly I'm not sure what they mean. We started Fuelly with an existing database of models and engines, and we're following the notation we were handed. Honestly we're not car guys, so we're lucky we can tell an inline-four from a V6. I know I couldn't before I helped create this website.
Just think of the engine type as a rough guide here because it's up to users to pick the right one, and it's confusing.
True. The issue exists because we trust our users to enter accurate information. We do try to limit the choices to those engines in the system that make sense. But we also give users the ability to choose any engine we have available with some extra clicks. Anyone can choose "other" from the list of available options, which gives them the choice of entering any engine in the system for their vehicle. 2 and 3 cylinder engines do exist, so we can't remove them altogether.
So a few folks with Jettas probably were poking around with the system and entered what they thought was correct--or maybe they were just messing around. It's all part of the trade-offs we live with. We've traded flexibility for potential inaccuracy.
By far we have more Jettas than any other vehicle in the system, so you're also going to find the most errors there because of sheer volume.