A number of vehicles use a diesel-electric powertrain for providing locomotion. A diesel-electric powerplant includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors. Before diesel engines came into widespread use a similar system, using a petrol engine and called petrol-electric, was sometimes used.
This kind of power transmission is used by locomotives (see that article for details), used for pulling or pushing trains. Diesel-electric powerplants have also been used in submarines and surface ships and some land vehicles. In some high-efficiency applications, electrical energy may be stored in rechargeable batteries, in which case these vehicles can be considered as a class of hybrid electric vehicle.
The first diesel motorship was also the first diesel-electric ship, the Russian tanker Vandal from Branobel, which was launched in 1903. Steamturbine-electric propulsion is in use at least since the 1920s (Tennessee class battleships), the practice of using diesel-electric powerplants in surface ships has been a more recent development. The Finnish "coastal defence ship " Ilmarinen, laid down in 1929, was among the first surface ships to use diesel-electric transmission. Later the technology was used in diesel powered icebreakers.
Some modern ships, including cruise ships and icebreakers, use electric motors in pods called azimuth thrusters underneath to allow for 360° rotation, meaning that the ships are far more maneuverable.
Some vehicles also use gas turbines in the same way. In fact, some use a combination: the Queen Mary 2 has a set of diesel engines in the bottom of the ship plus a gas turbine near the top exhaust tower. All are used for generating electrical power, and none of the ship's propellers are directly connected to any engines.
When the diesel engine was first installed in submarines before the First World War, it revolutionized submarine tactics because its range (or operating time) far surpassed that of the gasoline engine, and the lower volatility fuel meant that fuel and vapors were far less prone to catch fire or explode if they leaked into a submarine cabin. The fuel was also easier to stow. In submarines, the engine is connected to generators to produce electric energy that is stored in batteries for running underwater where oxygen is not available to feed the engines. It had been standard for them to use a driveshaft directly connecting the diesel engine, generator and propellers. There were a variety of clutch mechanisms for various connections as well. However, the long driveshaft has often been a source of trouble, also producing noise and vibration.
Some Soviet submarines had three propellers, and could be used in a variety of ways: each running on its diesel engine; either the central one or the outer two could each be connected to a diesel engine with or without the other propeller running on electric; or the engines could via snorkel be recharging the batteries while the central propeller was quietly running on its electric motor; or all three could be running on electric motors.
The diesel engine performance was critical for a conventional submarine's success. Navies imported and copied successful designs. The Germans had some excellent diesel designs for their U-boats, but they also had some designs which were not so good. The Americans had a similar history; their last diesel engine design was radial in form, its driveshaft axis angled vertically. These designs were subsequently abandoned. Older submarines had to be cut in half through the engine room and proven engines installed in a lengthened hull section to replace the unreliable but space-efficient designed engine. Since the correction, European submarine diesels have shown advances.
Modern diesel-electric submarines don't have a direct connection of the diesel engine to the propeller anymore: The usually single propeller is driven directly by an electric motor. Two or more diesel-generators provide electric energy for loading the batteries and/or driving the electric motor. This mechanically insulates the noisy engine compartment from the outer pressure hull and reduces the acoustic signature of the submarine. Even some nuclear submarines decouple their reactor room this way, e.g. all French classes, like the Rubis and Redoutable and the Chinese Type 093 class, have turbo-electric propulsion.
In the 1920s, diesel-electric technology first saw limited use in switchers (or shunters), locomotives used for moving trains around in railroad yards and assembling and disassembling them. One of the first companies to offer "Oil-Electric" locomotives was the American Locomotive Company. The ALCO HH series of diesel-electric switcher entered series production in 1931. In the 1930s, the system was adapted for streamliners, the fastest trains of their day. Diesel-electric powerplants became popular because they greatly simplified the way motive power was transmitted to the wheels and because they were both more efficient and had greatly reduced maintenance requirements. Direct-drive transmissions can become very complex, considering that a typical locomotive has four or more axles. Additionally, a direct-drive diesel locomotive would require an impractical number of gears to keep the engine within its powerband; coupling the diesel to a generator eliminates this problem. Some attempts were made at using hydraulic fluid as a transmission medium, and it proved to be somewhat more efficient than diesel-electric technology. However, the complexity of both the direct-drive and hydraulic systems meant that breakdowns were more common.
The batteries, carried generally on top of the bus (although some hybrid models are indistinguishable from conventional models, as shown to the right), are charged both by the diesel engine and by capturing energy from braking action. Diesel-electric hybrid buses are generally quieter than conventional (only-petroleum) diesel buses.
The two main providers of hybrid systems for diesel-electric transit buses include Allison Transmission and BAE Systems. Allison provides the EP40 and EP50 parallel hybrid systems, while BAE Systems provides the HybriDrive series hybrid system. New Flyer Industries, Gillig Corporation, and North American Bus Industries are major customers for the Allison EP hybrid systems, while Orion Bus Industries is a major customer for the BAE HybriDrive system.
Some hybrid buses are designed to receive most of their operating energy from electricity. Also, a driver may be able to choose to use only the battery system instead of the diesel engine. Some hybrid vehicles only use the electric battery when accelerating or idle, but otherwise operating on diesel.
- Big mining machines like the Liebherr T 282B dump truck or LeTourneau L-2350 wheel loader are powered that way.
- Also NASA's huge Crawler-Transporters are propelled diesel-electrically.
- Mitsubishi Fuso Canter Eco Hybrid is a diesel-electric commercial truck.
- International DuraStar Hybrid diesel-electric truck. 
- Dodge is conducting fleet tests of a diesel-electric version of the Dodge Sprinter. 
- Citröen C-Cactus is a diesel-electric hybrid car 
- Robert Bosch GmbH is also supplying hybrid diesel-electric technology to Peugeot 308 .
- Chevrolet Volt/Opel Flextreme is a plug-in diesel-electric hybrid.
- The "Third-Millennium Cruiser" was an attempt to commercialize a diesel-electric automobile in the very early 1980's
- Volkswagen boss Martin Winterkorn has confirmed the company plans to build compact hybrid vehicles. There will definitely be compact hybrid models, such as Volkswagen Polo and Volkswagen_Golf, and without any great delay", with gasoline and diesel engines. Also underway at Volkswagen's Braunschweig R&D facilities in Northern Germany is a hybrid version of the next-generation Touareg, due in 2010. All future VW models to have hybrid option. “Future VW models will fundamentally also be constructed with hybrid concepts,” VW head of development Ulrich Hackenberg told Automobilwoche in an interview. Hackenberg mentioned that the car based on the Up! concept seen at Frankfurt motorshow , as well as all future models, could be offered with either full or partial hybrid options. The rear-engine Up! will go into production in 2011. VW showed a Golf Diesel Hybrid at the 2008 Geneva Motor Show.  Nothing has been told about plug-in hybrid option. 
- One can also install an aftermarket hybrid powertrain to a diesel vehicle (such as one from California Motors).
eCycle Inc had plans to produce a diesel-electric motorcycle getting 180 mpg with a top speed of 80 mph (Expression error: Missing operand for *. ) and a target retail price of $5,500.   but has since decided not to sell a complete hybrid motorcycle but try to become a key supplier to enable other companies to make hybrid motorcycles.
Other land vehicles
Diesel-electric propulsion was tried on some military vehicles, such as tanks. One example was the ill-fated Maus tank. Currently no tank uses this principle for movement, but it's quite common to train the turret and/or guns with electric motors powered by diesel or turbine APUs.
The U.S. military is considering a replacement for its HMMWV utility vehicle which would use a diesel-electric propulsion system. Such a vehicle could operate its electrical systems for an extended period without running the engine, due to the large battery reserves. When stealth is desired, it could drive using only electrical power for a limited time.
- Battery semi-trailer.
- Diesel-electric locomotive.
- Diesel-electric multiple unit.
- Electric vehicle.
- Federal Transit Administration.
- List of automobile manufacturers.
- Other petroleum electric hybrid vehicle.
- Hybrid Powertrains.
- International starts hybrid production - eTrucker
- Dodge Sprinter Plug-in Hybrid Electric Vehicle (PHEV)
- Dodge - 2007 Sprinter - Passenger Vans, Cargo Vans
- Frankfurt Green: Citroen C-Cactus - The Car Connection
- Bosch says it has contract for diesel-hybrid parts - Automotive News Europe
- Compact Hybrid Coming From Volkswagen
- 2007 Frankfurt Auto Show: Volkswagen Up!
- VW's Golf Diesel Hybrid Debuts. Tell Us Why You Love It | Autopia from Wired.com
- Report: All Volkswagen models to have hybrid option
- Diesel hybrid car also taps the sun - Green Machines - MSNBC.com
- Hybrid Diesel Electric Motorcycle
- eCycle Hybrid Motorcycles
- eCycle, Inc. | Hybrid Motorcycle
- EERE Clean Fleet Guide by vehicle type.
- Hybrid-Vehicle.org: Information on hybrid vehicle history, hybrid vehicle technology and practical application of hybrid technology in a broad spectrum of vehicles..
- Diesel Forum: diesel hybrid corner.
- Northeast Advanced Vehicle Consortium.
- Markham’s Clean Air Hybrid Bus by FIBA Canning Inc.
Metro Transit with hybrid buses
- US: 11 transit agencies unite to buy 157 hybrid buses.
- Trimet Hybrid Diesel-Electric Bus Fleet.
- MTA NY Orion electric hybrid buses.
- King County Hybrid Bus Program.
- SF Muni Acquired Buses With Latest Hybrid Bus Technology.
- Western Consortium Orders 157 GM Hybrid-Powered Buses.
- San Francisco Streets to Get Diesel-electric Hybrid Buses.
- West Philly students and teachers built the "Attack", a biodiesel and electric hybrid that gets 50 mpg.