What's The Difference Between Mack LR And MD Trucks?

Mack is one of the most popular semi-truck brands in America right now, and it boasts a wide and varied selection of trucks. The current line-up consists of the Pioneer, Anthem, Granite, TerraPro, Pinnacle, LR, and MD series trucks. Let's look at the latter two models, the LR and MD series trucks, and explore the key differences between these two offerings.

To those unfamiliar with the trucking world, it may seem as if all trucks are designed for the same job, which is essentially to haul goods from one place to another. However, digging a little deeper reveals there's a world of difference between the various available styles of trucks. Mack trucks, with their signature bulldog hood ornament, are no exception to the rule.

The most obvious difference between the two truck styles is their design. The LR series is a cab-over truck, which is immediately obvious from the flat front — a design made possible by having the cab over the engine, negating the need for a hood. The MD, however, takes a more conventional approach, with a short-hood design that enables the cab to sit further back. As a general rule, hooded trucks like the MD are more aerodynamic than cab-over models, although this will make little to no difference at urban speeds.

The differences between these two types of trucks don't end with the design, either. Mack has engineered and built the MD trucks as class 6 and class 7 models, which indicates that the gross vehicle weight (GVW) will be between 19,001 and 26,000 pounds (class 6), or between 26,001 and 33,000 pounds (class 7). Mack states that the MD sports a GVW between 25,995 and 33,000 pounds, whereas the LR is considerably heftier, with a GVW between 43,000 and 72,000 pounds.

This higher GVW of the LR sees it classified as a class 8 truck, making it a heavy-duty truck. The smaller MD, in comparison, is a medium-duty model. Mack also builds the two trucks for different uses. The LR is designed to excel as a refuse truck, whereas the MD seemingly suits a wider range of applications, including refuse, regional haul, and vocational use.

There are also differences under the hood, even though both trucks use Cummins diesel engines. The LR sports an 11-liter MP7 engine with up to 375 hp and 1,360 lb-ft of torque. Conversely, the MD makes do with a Cummins B6.7 engine capable of churning out a maximum of 300 hp and 660 lb-ft of torque.