Why has diesel power for motorcycles never taken off? Diesel engines are fantastically economical, produce massive torque, are simple to maintain, and are generally very reliable. On the downside, a diesel engine is heavy, but is that enough to explain why there have been so few diesel-engined motorcycles in history, when you consider all the positives?

To celebrate these manufacturers which have dared to be different, here is our list of the top ten diesel-powered motorcycles:

It looks like a classic ‘60s British bike, but the German Sommer 462 is actually available to buy brand-new.

Sommer has been building these motorcycles since the early 2000s and, if it looks very much like a Royal Enfield, then that is no illusion as the inspiration for the model came from the Royal Enfield diesel model of the late 1990s (see below).

When Royal Enfield pulled out of the diesel market due to poor sales, Sommer took up the reins, sourced a 462cc single cylinder diesel engine, installed it into a Royal Enfield frame, and used other RE components.

The engine might only produce 11 horsepower and the top speed is a slightly pedestrian 65mph, but it will do 300 miles on a tank of gas (and the tank really isn’t that big!)

There are four gears in the gearbox and the final drive is via belt. The Sommer 462 is handmade in Germany and that pushes the price up to around $13,000, but what you lose in performance, you’ll gain at the gas pump.

There seems to be a rule amongst major manufacturers that any new motorcycle concept has to be as ugly as possible and no one has ever really explained why this should be! Surely you would want to generate as much interest as possible and, while challenging looks might get the bike remembered, it likely as won’t help it sell!

Hero Motorcorp is one of the largest producers of motorcycles in the world and the RNT is much more than simply a diesel-powered scooter. It’s actually a diesel hybrid as it not only comes with a 150cc single-cylinder diesel engine that produces 13.5 horsepower and 26 pound-feet of torque, but also features a 1.3 horsepower electric motor in the front hub, making this a two-wheel-drive scooter.

If you can get past the looks, it appears to be rugged and versatile with various luggage carrying options. The engine can also be used as a generator to provide electricity if you are out in the wild which, of course, you would be on a scooter!

There’s no word on whether it will ever make it to production but, if it did, it would be one of the more interesting motorcycles on the road.

The Track T800CDI is proof that innovation doesn’t have to equate to ugly or outlandish design. Looking for all the world like an adventure bike - a cross between Yamaha and BMW, we’d say - it has a whole dose of real-world practicality, despite its advanced specification.

It uses the turbocharged three-cylinder, 800cc engine from the Smart Car, producing 45 horsepower and 78 pound-feet of torque. Acceleration - not usually a diesel engine’s forté - is brisk at four seconds for 0-60mph and this is accompanied by an excellent 140 miles per gallon gas mileage.

Tall suspension, steel trellis frame, and Brembo brakes are all the right ingredients but it just wasn’t a success for some reason. The company started selling motorcycles in 2009 and reportedly sold 50 examples before stopping production in 2012, presumably so the company could concentrate on developing new models, perhaps in the electric field.

A lost opportunity, we’d have to say.

Very likely the most famous diesel motorcycle ever produced, and, almost certainly the only such bike produced by a major manufacturer.

RE produced its own 325cc diesel engine for the bike, which used standard Bullet chassis and running gear and which, even given a diesel engine’s good torque characteristics, could still muster only 6.5 horsepower and 11 pound-feet of torque, which isn’t much to push forward a 432-pound all-in weight. However, it was able to record up to 200 miles per gallon, even if it would take you all day to do 200 miles: top speed was 40mph.

It vibrated badly but it was rugged, simple, and reliable, although the death knell was sounded when the Taurus failed to meet even India’s emissions regulations and it was discontinued in 2000.

A brave attempt to do something different and not likely to be repeated.

Using diesel power for a motorcycle makes sense when talking about military applications: all the usual benefits - economy and reliability - combined with, in the case of the Hayes M1030, the ability to run on a variety of fuels - truck diesel, biodiesel, gasoline and even jet fuel, which adaptability is ideal for a military role, given that you never know what fuel might be available at any one time in the field.

The 670cc liquid-cooled engine will propel the bike to 90mph, while returning 96 miles per gallon. The US Marine Corps bought over 400 and they are also used by the British and other NATO forces as well. A civilian model was planned but the number of military orders prevented that idea from going any further.

Money is no object and you want something different in your garage? Well, the Neander Turbo Diesel might just fit the bill.

It’s a bike of extremes: a turbocharged parallel twin-cylinder, 1,340cc engine produces 112 horsepower and 144 pound-feet of torque. However, it weighs in at a rather porky 650 pounds, meaning that you’ll only record around 50 miles per gallon.

As you can see, it’s in the cruiser/muscle bike class but ready yourself for the price: $133,000! At that level, you’d have to do a lot of mileage to make your money back but maybe that’s missing the point?

The performance option! Powered by a Volkswagen 1200cc, three-cylinder turbodiesel engine, the power and torque figures are akin to a modern electric motorcycle: 180bhp and 250 foot-pounds.

It’s bristling with top-spec suspension, carbon wheels, Brembo brakes, and was slated to do about 140mph, achieving 95 miles per gallon along the way.

But, the economy wasn’t what the makers had in mind: this was designed to be a powerful and fast track bike, although that dream was ultimately left unfulfilled as it never went into production.

Back in time for the next diesel motorcycle. The Sidney Diesel of 1950 could very well be the first diesel-powered motorcycle.

The brainchild of one Arthur Sidney, he designed his own single-cylinder diesel engine which produced 14 horsepower, although the top speed was a meager 35mph. As the contemporary BMW R68 would top 100 miles per hour on 35 horsepower, the Sidney Diesel was very slow and there is no record of what kind of gas mileage he got, although it was surely impressive for the day.

However, as gas price wasn’t an issue in the early 1950s, maybe the Sidney Diesel was a bike before its time.

Something with a little Gallic (that’s French to you!) charm now. The Boccardo Aero was the brainchild of Louis Boccardo, who used both petrol and diesel engines from the Citroen AX back in 1987.

Only five were ever built: two with petrol engines producing 97 horsepower and three with diesel engines, producing 59 horsepower, all using shaft final drive.

As with many small-production motorcycles, styling was not the Aero’s strong point, although the diesel engine produced sufficient torque to make the fitting of a sidecar a logical development.

Another Indian diesel-powered motorcycle, the Sooraj Sunbeamer was manufactured between 1990 and 2010.

Not the most attractive bike ever designed, the 325cc single-cylinder diesel engine is washed by a 20-liter gas tank which we’d imagine would give the bike a 400-mile range, if you could bear to sit on it for that long!

As for the looks, well, it won’t win any beauty contests!

Diesel engines tend to be slow revving, noisy and heavy, with a lot of vibration, making them unsuitable for motorcycle installation, where light weight is seen as being of paramount importance.

No, there is currently no major motorcycle manufacturer producing diesel production motorcycles.

Royal Enfield did produce a diesel-engined motorcycle in the 1990s, but production had to stop in 2000 when it couldn’t meet emissions regulations.

There are, but they are produced in tiny numbers by specialist companies and tend to cost a lot of money.