How many miles to the gallon does a school bus get?

A Skoolie generally won’t have the greatest fuel mileage in the world, but then again, neither do similarly sized manufactured RVs. It’s kind of to be expected when you drive a vehicle that is about as aerodynamic as a loaf of bread. However, as we always tell people, a skoolie’s fuel economy is not great for a vehicle, but it’s pretty dang good for a house.

So, how many MPG does a skoolie get? On average, you can expect to get between 6 and 12 MPG depending on the size and weight of your bus. Specifically, you’ll be looking at anywhere between 10 and 12 MPG for a short bus, 6 to 10 MPG for a mid-size bus, and 9 to 10 MPG for a full-size bus. 

In this article, I’ll share MPG related details about our 22 foot short bus and two of our fellow skoolie owners with larger buses will share their experiences as well. But first, let’s cover some of the factors that play a role in skoolie MPG and overall fuel economy.

Gas vs Diesel Skoolie

Diesel engines are by nature more fuel efficient than gas engines, and diesel is more energy-dense than gasoline. So, with both of those factors in mind, a diesel bus can go anywhere from 20-35% further than a gas bus on each gallon of fuel. And, although diesel is often more expensive at the pump, you’re getting more bang for your buck.

Diesel engines also typically last much longer than gas engines. A bus with a gas engine might make it 200,000 miles before needing a complete engine overhaul, while some diesel engines can go as far as 1.5 million miles before needing serious maintenance. This is why it’s completely normal to see 30-year-old buses cruising around the country!

However, diesel engines are often more expensive to maintain than gas engines, and if something does go wrong, it can be quite costly to fix it. But, considering most used school buses can be purchased for $5,000 or less, that should leave you with some money to set aside for potential repairs.

Finally, it can be more difficult to find diesel than regular gas, but in almost 3.5 years on the road, we’ve only had this issue come up once.

How To Improve Your Skoolie’s Gas Mileage

1. Choose an Efficient Engine

Obviously, different engines consume fuel at different rates, and short buses will have completely different engines than a 40-footer with a pusher (rear engine). My best advice here is to decide what size of bus you want, and then research engines for that specific length.

The larger the bus, the bigger and beefier the engine will be, but there is still some variation here which is why it’s important to carefully select what engine you want to shop for. 

We did not do this, and we ended up getting the smaller and less powerful of the two engine options for our bus size. This hasn’t been a huge detriment, but it would be nice to have a bit more power on those mountain passes. There are people on the internet who love to give us unwarranted advice/criticism for choosing “the worst possible engine” but here we are, still chugging along!

2. Keep Size and Weight Low

This is perhaps one of the biggest factors for fuel economy. Each bus has its own Gross Vehicle Weight Rating (GVWR), which refers to the maximum amount of weight that a vehicle/engine combo can handle, including the vehicle itself, passengers, and cargo.

Naturally, the closer you come to the GVWR, the worse fuel mileage you will get. Keep your build as light as possible to prevent the engine from having to work too hard and to get the best possible fuel mileage.

3. Select Proper Tires

Just like on a car, the type of tires you put on your skoolie will factor into the overall fuel efficiency. Most people aren’t putting MPG-killing off-road tires on a bus, but still, it’s something to think about. The knobbier the tires, the worse your fuel economy.

4. Maintain an Optimum Driving Speed

Most vehicles have a sweet spot, aka the maximum speed you can drive before you start dealing with a dramatic decrease in fuel efficiency. For us, it’s about 60 MPH in ideal driving conditions, and much slower if there’s a hill, wind, etc. However, one of the reasons we love this lifestyle is that we rarely have somewhere pressing to be, so we are just fine with trundling along in the right lane.

5. Choose a Bus with a Large Fuel Tank Size

While the fuel tank size doesn’t directly impact your fuel efficiency per-se, it’s still something to consider. We bought our bus without even thinking to check the size of the fuel tank, and it ended up being 55 gallons, which we are very happy about because it means we have a low chance of running out of diesel between stations – which can be a real concern in parts of the west where towns are few and far between.

Some big buses only have 25-gallon tanks, and if you’re only getting 6 MPG, you’ll need to fill up every 150 miles or less. Getting diesel is sometimes no easy feat, especially if you have a big bus in a small city gas station, or if you’re in a sparsely populated area where there isn’t diesel available for hundreds of miles at a stretch.

Environmental Factors That Can Affect Fuel Efficiency

Road Grade and Condition – This is common sense, but obviously you will get worse gas mileage if you are driving up and down mountains as opposed to cruising on flat ground. You’ll also need to be careful that your engine doesn’t overheat if you are climbing mountains – which can generally be achieved through regular maintenance and by not overloading your skoolie. 

And, as any car owner knows, mileage will be different on city streets versus highways. The road condition also factors into gas mileage, with rougher roads leading to less optimal fuel mileage. We’ve found that some states have perfectly smooth roads while others (ahem, Arizona) are less than ideal.

Wind – Again, skoolies don’t have great aerodynamics, so a headwind can be a real detriment to fuel mileage. We’ve driven through high winds on flat ground where we’ll have the pedal to the metal and still be struggling to accelerate and burning through diesel like crazy.

However, if you manage to find a tailwind as you’re driving, it’s your lucky day! On one drive we got almost 15 MPG because it was all on a smooth, flat highway with a tailwind.

Altitude – Interestingly, your engine may get better fuel mileage at higher elevation, but you will also lose engine power. This is more applicable for gas engines than diesel, but we have experienced issues with our turbo sensor getting freaked out if we change elevation and temperature too dramatically or too quickly on a drive.

So, note that if you change elevation significantly, it may impact your fuel efficiency.

Real World MPG Data From Skoolie Owners

Alright, so now that we’ve looked at many of the factors that contribute to how many MPGs a skoolie will get, let’s look at some specific real-world examples.

Our Short Bus Fuel Economy: 10-12 MPG

My boyfriend and I bought our bus Stu (@stu.the.bus) in 2017, converted it ourselves, and have been on the road since April of 2018. To keep things simple, I’ll answer the same questions I asked our fellow skoolie owners:

Can you give us a quick rundown of your bus’ stats?

We have a 2005 Ford E-450 van front with a 2007 Thomas Minotour bus body. It’s 22 feet long and it has a 6.0L diesel engine. Fully loaded, it weighs about 12,000 pounds.

What is your average MPG?

We get between 10 and 12 MPG, depending on all of the above factors.

How big is your fuel tank?

We have a 55-gallon tank, which sucks when we have to fill it up completely to the tune of $150 or more, but we love that we can drive well over 500 miles on one tank of diesel.

Did you look for a specific engine/fuel type/tank size/MPG when you were shopping for a bus?

No, we basically had no idea what we were doing except that we wanted a diesel. As I mentioned, we didn’t even know the fuel tank was that big until much later. We also probably would’ve tried to find a similar bus but with the 7.3L engine, although our 6.0L has actually been a champ so far, so no regrets.

Any quick comments or advice for someone looking to purchase a bus in regards to fuel efficiency?

Look for the most powerful engine you can get relative to the overall size of your bus, and keep your build as light as possible. Also, keep your driving speed moderate to help stretch your MPG as I mentioned above. We don’t push our engine hard at all, primarily to keep it functioning smoothly but also to get as good of fuel mileage as possible.

Braden & Vanessa’s Mid-Size Bus Fuel Economy: 6-10 MPG

I chatted with Braden and Vanessa (@chumbothebus) about their fuel economy and here’s what they shared:

Can you give us a quick rundown of your bus’ stats?

“Our bus, also known as Chumbo, is a 2006 International 3300 with a Navistar DT466e engine and Allison 2500 transmission. It is 32 feet long bumper-to-bumper, with an additional 4-foot rear rack which holds our mountain bikes, propane, extra fuel (gas and diesel), and our Honda CRF250l Dual Sport that we use for exploring.

We do not have the weight of our bus from when we purchased it, but after our build along with all of our belongings and full tanks of fuel and water it weighs right around 21,500 pounds. The GVWR of our bus is 27,500 pounds, so we’re a good bit under that.”

What is your average MPG?

“Our average MPG seems to fluctuate based on road types (highway vs. mountain grades) so our best estimation so far is between 6-10 MPG.”

How big is your fuel tank?

“Our fuel tank holds 60 gallons of fuel. Unfortunately, it’s very hard to actually FILL our tank because the cutoff point is around 95%. This makes it hard to calculate fuel mileage due to the gauge not being able to read the tank volume as full. Sometimes we can maneuver the pump to fill the tank more, but it doesn’t always work.”

Did you look for a specific engine/fuel type/tank size/MPG when you were shopping for a bus?

“We mainly looked for a specific engine over everything else, outside of the size we wanted. We knew that gas buses had low MPG and weren’t known for lasting high miles on the engine, so we wanted to look for a diesel. Because a bus is such a large vehicle, we were prepared for getting low MPG, so that wasn’t a large concern for us.

We also didn’t worry too much about the tank size. Our requirements were a DT444 (or Ford 7.3L Powerstroke), DT466, or a Detroit under the years of 2007 due to modern emission changes that can be costly to repair. Ultimately, we decided between two buses, one having a DT444 and the other a DT466e. We chose ours mainly due to the other having more rust than we were comfortable with.”

Any quick comments or advice for someone looking to purchase a bus in regards to fuel efficiency?

“The best advice we can give is to be aware that no matter the vehicle, if it’s large you most likely won’t get very great MPG. A bus is basically a curved box so aerodynamics aren’t the best. However, if you plan your trips properly and make arrangements to stay in areas for a few days at a time, the cost of fuel can become less of a worry.

We have done multiple days in a row of traveling and it can really add up. We typically drive 3-4 hours maximum at a time, and when we get to a destination we like to stay for upwards of a week, sometimes two. For us, we always plan to fill the tank as soon as we can once we’re around half full.

This helps us not have to worry about getting to a fuel stop when the tank is low, and if anything happens or we need to leave for an unexpected reason, we have enough fuel to get to our next destination or fuel stop safely. “

Steven & Karin’s Full-Size Bus: 9-10 MPG

And finally, I talked with Steven and Karin (@nomadic_lady_g) about their full-size bus:

Can you give us a quick rundown of your bus’ stats?

“2001 International Genesis bought with 107k miles, 35 feet long, DT466 engine with an Allison 545 transmission. Fully converted, it weighs 22,500 pounds fully loaded.”

What is your average MPG?

“We get around 9-10 MPG with a tow car attached. If I’m doing a lot of throttle work or stop and go we get 9 MPG but if I’m just cruising on the interstate we get 10 MPG.”

How big is your fuel tank?

“35 gallon tank (in hindsight I should’ve researched before I bought) though by appearance it was 50 gallons. Hasn’t been an issue yet, but as I dip under half a tank my wife starts looking up gas stations.”

Did you look for a specific engine/fuel type/tank size/MPG when you were shopping for a bus?

“We were shopping for length, tire tread, and engine combos. I could be very wrong but I figured for us a 5.9L Cummins would be always working too hard. So I went with the DT466, unfortunately the 545 was my only real choice in Florida and it has been the weak link. We’re heading out west now and I’m wondering when I’ll find a road that’s too much.”

Any quick comments or advice for someone looking to purchase a bus in regards to fuel efficiency?

“As for comments I think everyone needs to build them to what they need it to do, not what they see on social media. Just because a lot of people are doing roof raises and all these other things doesn’t mean it’s the only way to do it. I think it’s ridiculous that everyone is putting all that weight on their ceiling with tongue and groove or spending $1,000 on Dynamat.

At the end of the day these are decommissioned buses we’re trying to travel with. They shouldn’t be 30,000 pounds. The amount of auction buses breaking down everywhere is making it very hard to find roadside assistance and insurance now.

Be prepared for anything to go wrong on the road and be ready to handle it with a sense of urgency. Bring tools. And the road is a lot more expensive and challenging than I thought. Especially if you have pets and you can’t find proper temperatures to travel in without being plugged in.

Also yes the scenic roads are prettier and you may miss sights by not using them, but the grades and road conditions you may find are very challenging. I learned going through Georgia that unfortunately the interstates are my friend. The tow car has been our best friend so if you can, you should bring one.

But if it wasn’t for our pets we’d be in a short bus or van and life would be a little easier but it’s home and I wouldn’t change it. We also built the bus to be heavier on the driver’s side to complement the crowns in the roads so we’re not always pulling down into the shoulder and that’s helped a lot.”

Choosing a Fuel Efficient School Bus

Honestly, there are so many factors that go into this that it’s hard to say any one bus is better than all others. The bottom line is that no skoolie is going to get particularly impressive fuel mileage, although you can do yourself some favors by carefully selecting the engine, keeping your build lightweight, making sure you have a large fuel tank, and driving at a controlled speed.

Think you’ve got the most efficient skoolie out there? I’d love to hear about it!

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