Quick answer: Convert a Ram ProMaster if you want the most usable interior for the least money and you plan to sleep sideways. Convert a Ford Transit if you want gas-engine running costs with real all-wheel drive and the tallest ceiling of the three. Convert a Mercedes Sprinter if you are going long-haul, want 4×4 with diesel range, and care about resale value.
That is the short version. The longer version matters, because a van conversion is a five-figure decision layered on top of another five-figure decision, and the platform you pick locks in your ceiling height, your bed orientation, your service costs and your resale value for the next decade. Get it wrong and you will spend the whole build fighting the van.
Here is how the three full-size vans actually compare for a camper build, from a maintenance and ownership point of view rather than a lifestyle one.
The three vans at a glance
| Spec (2026 models) | Mercedes Sprinter | Ford Transit | Ram ProMaster |
| Drivetrain | RWD standard, 4×4 available | RWD standard, AWD available | Front-wheel drive only |
| Engine | 2.0L turbo-diesel, 170 or 211 hp | 3.5L V6 gas, 275 hp; EcoBoost V6, 400 lb-ft | 3.6L Pentastar V6 gas, 276 hp |
| Transmission | 9-speed automatic | 10-speed automatic | 9-speed automatic |
| High-roof standing height | 79.1 in | 81.5 in | Lowest of the three |
| Max cargo volume | Up to 488 cu ft | Up to 487 cu ft | Up to 524 cu ft |
| Max payload | Around 4,100 lbs on common 2500 builds | Up to roughly 5,100 lbs on T-350 HD | Up to roughly 4,800 lbs |
| Turning diameter | Average for class | Average for class | 36 ft, best in class |
| Buy-in cost | Highest | Middle | Lowest |
Figures vary by wheelbase, roof height and GVWR rating, so always confirm against the exact configuration you are ordering.
Ram ProMaster: the most interior for the least money
The ProMaster is the outlier of the group, and the reason is its front-wheel-drive layout. With no driveshaft or rear differential under the floor, Ram drops the load floor to around 21 inches. That is the lowest step-in height in the class, and inside a camper it pays off twice: you get more usable ceiling for a given exterior height, and your garage area under the bed gets deeper.
The bigger win is width. The ProMaster’s body sides are close to vertical rather than tapered, and it is the widest of the three inside. For most people that means you can run the bed crosswise instead of front-to-back, which frees up two to three feet of van length for a galley, a shower or a workspace. On a Sprinter or Transit, a crosswise bed usually only works for shorter sleepers or with flare kits bolted to the walls.
Ram also improved the ownership case for 2026 with a 10-year or 100,000-mile limited powertrain warranty, which is the strongest coverage in the segment. The Pentastar V6 is a well-understood engine that any independent shop can service, and oil change intervals run to 10,000 miles. You can check the current configuration details on Ram’s official ProMaster capability page.
Where the ProMaster falls short
- No all-wheel drive, ever. Front-wheel drive is genuinely decent in snow because the engine weight sits over the driven wheels, but it will not get you up a rutted forest road. If your build plan involves trailheads, this is disqualifying.
- Least standing height. The high-roof ProMaster gives the least headroom of the three. Most people under six feet are fine; taller builders end up ducking, and you lose margin once you add a floor and ceiling.
- Gas mileage. Owners generally report somewhere between 14 and 20 mpg depending on load and conditions, which is the weakest of the three on long trips.
- Weakest resale. Converted ProMasters simply do not command what converted Sprinters do on the used market.
Ford Transit: the sensible middle
The Transit has quietly become the default choice for a lot of builders, and the reason is that it removes most of the compromises without adding Mercedes money.
Start with the ceiling. The high-roof Transit gives 81.5 inches of interior height, the tallest of the three. After you install a subfloor and a ceiling, you still have room for a fan and a tall person standing under it. That single number solves a problem that plagues a lot of ProMaster builds.
Then the drivetrain. Ford’s Intelligent All-Wheel Drive is available across body lengths, roof heights and engine choices, and critically it does not raise the load floor or the seat height. You get traction without giving up interior volume, which is the trade-off you make on a lifted 4×4 Sprinter. Payload is strong too, with the heavy-duty T-350 configurations rated to roughly 5,100 pounds, and payload is the spec most first-time converters underestimate. Water, batteries, cabinetry and gear add up fast.
Powertrain-wise you pick between the naturally aspirated 3.5L V6 and the twin-turbo EcoBoost V6, which brings 400 lb-ft of torque. Both are gas, both use a 10-speed automatic, and both can be serviced at any Ford dealer in the country. That last point is worth more than it sounds when you are 400 miles from home.
The Transit’s popularity with builders reflects this. Shops that used to be Sprinter-only now run Transits through the shop in similar numbers, and several offer near-identical layouts on both platforms. Boulder-based builder The Vansmith, for example, publishes a full line of Ford Transit camper van builds alongside its Sprinter builds, which is a useful reference point if you want to see how professionals lay out the same footprint.
Where the Transit falls short
- Narrower than the ProMaster. Crosswise sleeping is tight without wall flares.
- Wind noise. High-roof vans are all noisy, and the Transit is no exception at highway speed. Good insulation work mitigates it; a bad insulation job makes it worse.
- Gas thirst on the EcoBoost. The torque is lovely. The fuel bill on a loaded camper is not.
Mercedes Sprinter: the long-haul and off-pavement pick
The Sprinter is the van the camper industry was built on, and it still wins on the two things that matter most to full-timers: range and capability.
The 2.0L four-cylinder turbo-diesel comes in 170 hp and 211 hp versions, both paired to a 9-speed automatic. Diesel means better fuel economy under load and a longer range per tank, which is exactly what you want when your van weighs 9,000 pounds fully built and you are crossing Nevada. High-roof models give 79.1 inches of standing height, and the 170-inch and extended wheelbases give you the longest usable floor of any of the three. Full specs by wheelbase and roof height are listed on the official Mercedes-Benz Sprinter cargo van page.
Then there is 4×4. Mercedes offers a genuine all-wheel-drive system on the high-output diesel, and it is the reason Sprinters dominate the adventure-van category. Combined with the strongest resale value of the three, a well-built Sprinter is closer to an asset than a depreciating vehicle.
Where the Sprinter falls short
- Cost, up front and ongoing. It is the most expensive van to buy and the most expensive to maintain. Diesel service, DEF, and Mercedes parts pricing all stack up.
- Service network. Not every Mercedes dealer services Sprinters. You need a commercial-certified location, and in rural areas those can be hundreds of miles apart. Plan for that before a cross-country trip.
- Tapered walls. The Sprinter’s body sides curve inward more than the Transit’s or ProMaster’s, which complicates cabinetry and eats usable width at shoulder height.
Five decisions that actually pick your van
Ignore the badge for a moment. Answer these five questions honestly and the choice usually makes itself.
1. How tall are you?
Measure yourself in shoes, then add roughly two to three inches for the subfloor and ceiling you will install. If that number lands above 76 inches, the ProMaster is probably out and you are choosing between the Transit and the Sprinter.
2. Which way will you sleep?
A crosswise bed is the single biggest space saver in a van conversion. If you and your partner are both under about 5’10”, the ProMaster lets you do it in a shorter, cheaper van. If not, plan on a lengthwise bed and pick the platform on other merits.
3. Where does the van actually go?
Paved campgrounds and city street parking: front-wheel drive is fine, and the ProMaster’s 36-foot turning circle is a genuine daily-driving advantage. Snow and gravel: Transit AWD. Real dirt roads and trailheads: Sprinter 4×4.
4. Diesel or gas?
Diesel makes sense if you cover long distances regularly and want maximum range. Gas makes sense if your van sits for weeks between trips, if you want any shop in any town to be able to fix it, and if you want lower routine maintenance costs. For most weekend and part-time users, gas is the pragmatic answer.
5. What is your real budget, including the build?
The van is roughly half the project. A DIY conversion typically runs $10,000 to $30,000 in materials depending on how much electrical and plumbing you install. A professional conversion generally starts around $45,000 on top of a van you already own, and turnkey packages run well north of $100,000. Buying the cheapest van and running out of money halfway through the build is the most common way these projects fail.
So which van should you convert?
- Budget-conscious first build, mostly paved travel: Ram ProMaster. Most interior per dollar, easiest to drive and park, cheapest to service.
- All-round daily driver and weekend camper: Ford Transit. Tallest ceiling, AWD without losing floor height, gas engine serviceable anywhere.
- Full-time living, long distances, or off-pavement: Mercedes Sprinter. Diesel range, real 4×4, best resale.
There is no wrong answer here, only mismatches. Every one of these three platforms has thousands of successful conversions on the road. The builds that go badly are almost always the ones where somebody bought the van first and worked out the layout afterward.
Frequently asked questions
Which van holds its value best after conversion?
The Mercedes Sprinter, by a clear margin, followed by the Ford Transit. Build quality matters as much as the platform, though. A professionally built Transit will typically outsell a poorly finished Sprinter.
Can you convert a low-roof or medium-roof van?
You can, and people do, but you will be sitting rather than standing. If you want to cook and change clothes indoors, go high roof. The exception is if garage clearance is a hard constraint at home, since high-roof vans approach or exceed a standard 7-foot residential garage door.
Is front-wheel drive really a problem in winter?
Not for most people. With the engine weight over the driven wheels and a decent set of winter tires, a ProMaster handles snowy roads better than an unloaded rear-wheel-drive van. The limitation is loose surfaces and grades, not snow itself.
How much payload do I actually need?
A full conversion with cabinetry, insulation, a lithium electrical system, a full water tank and gear commonly adds 1,500 to 2,500 pounds. Add passengers and personal belongings on top of that. Weigh the finished van at a certified scale before you load up for a trip, because exceeding GVWR affects braking, tire life and your insurance position after an incident.
Should I buy new or used?
Used saves money but shifts risk onto you. Most professional builders work on 2018-or-newer vans, and many kit and cabinet systems are designed for that generation onward. If you plan to have any of the work done professionally, check the builder’s model-year cutoff before you buy.
