Like a hat, a car can “wear” its engine frontways or sideways. Unlike a hat, however, these different engine orientations aren’t just for looks. The alignment of an engine in a vehicle is very important and can have effects that range from its overall drivetrain style to how it handles.
The two main types of engine alignment in a vehicle are longitudinal and transverse. Longitudinal is when the engine runs parallel to the vehicle and the drive shaft, and transverse is when the engine is perpendicular to it. A longitudinally-oriented engine can be in the front middle, or the rear, while a transverse engine is usually mounted in the front.
This distinction between these two different types of engine alignment is an important thing to know about your car. Although there are some relatively simple ways to determine the difference between vehicles with transverse or longitudinally mounted engines, there are some important distinctions between the two that you might not immediately consider.
What's a Transverse Engine
While not universally true, the transverse engine isn’t really considered the enthusiast's option. Of course, there are plenty of exceptions to that, like the
Fiesta ST, but that being said, engines are generally mounted transversely for the sake of efficiency. It’s quite rare to see a transverse V8.
Transverse engines have become the default engine configuration for most vehicles out on the road today. Similar to the proliferation of the V6 as a standard type of engine, the main reason for the popularity of the transverse engine layout is both money and space optimization. Most of the important parts of the engine and transmission can fit within the engine bay alone, meaning that the vehicle’s cab is left unimpeded by a transmission tunnel or anything of the sort.
In fact, transverse engines are usually mated with a transaxle, which incorporates the transmission and final drive differential into a single unit. This allows for even further compression of the vehicle’s powertrain, freeing up even more room on the vehicle’s interior. This means more space for bigger and bigger infotainment screens, more cupholders, and of course, giant subwoofers.
There are a few benefits to transversely mounted engines besides vehicle design and packaging. Since most transverse-mounted engines are front wheel drive, the added weight of the engine over the front wheels improves traction on the driven wheels. That being said, that’s about all that transverse-mounted engines have to offer performance-wise.
One of the seriously limiting factors of this type of engine layout is the soft engine power cap that it imposes. Since the engine needs to be small enough to fit sideways in the engine bay, it’s hard to produce a lot of power. There are plenty of exceptions to this, but on the whole, smaller engines do mean less power. Recently, many manufacturers have opted to add turbochargers to their four-cylinder motors to help get around the smaller displacement. Additionally, it is significantly more difficult to swap in another engine into a vehicle with the transverse layout. While not impossible, the tight packing of everything in the engine bay means that there is substantially less “wiggle” room.
What's a Longitudinal Engine
A longitudinal engine layout is, in many cases, the ideal alignment for performance focused drivers. Basically any supercar that you can find out there today has a longitudinally-mounted engine.
Longitudinally mounted engines can be quite enormous and elaborate, and they can be positioned in many different locations throughout the car. Mid and rear-engined vehicles are possible to construct with a longitudinally mounted engine, and this means that a more ideal weight balance of the entire vehicle can be achieved.
Not everything is absolutely perfect with longitudinal engines, however. When compared to transverse engines, they require more effort to fit into vehicles, they can prove to be heavier, and they can cramp the interior of the vehicle. There’s a reason that most supercars don’t even bother with having a backseat.
The packaging of a longitudinal engine can prove to be difficult too, as the transmission is often rotating in a direction perpendicular to the movement of the car. This means that more drive shafts, differentials, and various other driveline components are needed to direct the power correctly.
Which One is Better
One engine layout isn’t necessarily better than the other, but they both have their own strong suits. Again, the better layout is the one the more closely conforms to your needs.
There is a staggering amount of variety in the construction of cars, so if you hunt hard enough, you can find an example of a rear-engined vehicle with a transversely mounted motor, or a FWD vehicle with a longitudinal engine.
The main reason you should be concerned with the style of engine mounting is if you are deciding which type of car to buy. If you are looking for a compact dailyable vehicle, then a vehicle with a transversely mounted engine is what you’re after. These cars aren’t necessarily boring transportation machines either, with the Fiesta ST and Focus ST/RS being glaring counterexamples.
If you are buying a car to be a dedicated performance machine, then you’ll likely want a longitudinally mounted engine. That being said, a Mustang is an easily dailyable vehicle as well! At the end of the day, the differences between these two engine layouts are wrapped up more generally in what type of car would you like to drive.