However, as modern vehicles are equipped with more and more electronics and components to reduce emissions, short trips are harmful to an engine, whether gasoline or diesel, or can greatly shorten the life of the engine.
Meaning for shorter journeys like to and from the shops, driving about town or if you have a shorter or slower-paced commute, a petrol engine will be more suitable. Diesel is also better for longer journeys because of it's on-average increased fuel economy.
Diesel Rule 3: Don't buy diesels for low mileage or inner city life. Also known as “diesel car city driving”, you want to avoid doing this. It's well known by petrolheads, but always worth explaining why. Driving at low speeds and short distances clogs up your Diesel Particulate Filter (DPF) quickly.
The damage begins with the liquids evaporating, leaving behind a thick substance that clogs the engine's moving parts. Ultimately, these parts will stick and begin to deteriorate. If given enough time, the engine will rust and fail to start.
Running low on diesel can also damage your fuel system. That's because the poorest-quality fuel settles at the bottom of the tank, and it's often full of sediment.
Unnecessary idling wastes fuel, causes air pollution and increases engine wear. An idling diesel engine produces much higher emissions than it would while using the same amount of fuel under load. Extended idling causes a build-up of soot inside the engine and results in a puff of black smoke when the engine revs.
So it is advised that drivers regularly give their diesel vehicle a good 30 to 50 minute run at sustained speed on a motorway or A-road to help clear the filter. However, not all drivers do this type of driving regularly – which is why manufacturers have designed an alternative form of regeneration.
The presence of water in diesel fuel systems causes a variety of problems. Water rusts steel and iron components, forming loose particles of iron oxide. These rust particles can quickly clog fuel filters.
Thousands of diesel engines fail prematurely each year aided by the presences of glycol, fuel, soot and water in the engine oil.
Myth: Diesel engines need to warm up at idle for 5 to 10 minutes or more especially on cold days before driving them. Fact: This is one of the most common myths about diesel engines. Most engine manufacturers recommend that newer diesel engines idle for no more than 3 minutes before driving.
Over the years the speed of 56mph has often been talked about as being the optimum speed. This was due to the old fuel consumption test being run at three speeds: urban, 56mph and 75mph – and 56mph was always, unsurprisingly, the most efficient of these. Typically, cars are most efficient at 45-50mph.
"You can get up to maybe 250,000 km or 300,000 km before a gas engine starts to make noise, or burn oil because it's wearing out, but a diesel can quite easily do 500,000 km and still be in excellent shape," says one certified mechanic I spoke with.
These days, there are engines with common-rail systems that allow fuel to be directly injected into the engine through a common line. So, there is hardly any need to run a diesel CRDI engine on a daily basis. After all, it takes a relatively shorter amount of time to warm up the fuel.
According to Bell Performance and Road and Track, customers who drive many highway miles often prefer diesel engines, since they are more efficient on these roads than gas engines. Diesel fuel simply packs more energy in every gallon than gas fuel, which makes it more economical overall.
1.0-1.2 Litre Engines
You'll get a good fuel economy out of them, as the smaller capacity means less fuel is used. This is great if you mainly do a lot of stop/start driving, such as in a city where there are lots of traffic lights, or if you usually make short journeys.
What are the pros of diesel? Diesels deliver more power at lower engine revs than their petrol equivalent. This makes diesels feel more suited to longer motorway trips because they're not working as hard as petrol engines to produce the same performance.
Cons of diesel cars
Diesel fuel usually costs more. Servicing can be more expensive, although you don't need to do it as often. Diesel cars produce a lot more NO2. Diesel engines can be slightly noisier.
Water causes damage to both fuel tanks and engine parts. Rust and corrosion in the tank create hard particulate that is passed along in the fuel, causing engine wear.
Allow Time to Warm Up the Engine
In order to start a diesel engine and keep it running in cold weather, you must make sure you allow plenty of time for your engine to warm up. If you do not let your engine warm up before driving, you will make it work harder than necessary, which will lead to problems later on.
Diesel's should be driven hard periodically. The reason for this is found in the large amount of carbon deposits that build up in diesel engines that are not opened up on occasion. A good way to do it is, simply to drop into a low gear while pulling a hill to get the RPMs up for several minutes.
Normal engine hours, in combination with mileage, would be 250 engine hours within 7,500 miles. But, if a fleet manager sees 500 engine hours for just 7,500 miles on the odometer, that's not good. Especially if they waited until after 7,500 miles to change the oil.