Five common concerns of diesel cars answered

As sales of diesel powered cars continue to soar in India, and with the rising cost of petrol, there are fresh buyers of diesel cars every day. And many of these are first time buyers of diesel cars, who have some concerns on how modern diesel cars perform.

It is true, that earlier diesels were noisy, smoky and unreliable, but with the advancement in technology, modern diesels are as good or if not better than an equivalent petrol engine. And diesels are generally more fuel-efficient as well. Also read: Why diesel cars give more mileage than petrol cars?

CarToq addresses five common concerns of diesel engines, going by the questions asked by community members planning to buy a diesel car.

#1 Lifespan of a diesel engine

Diesel engines are built much stronger and thicker than petrol engines, because they are high compression engines and work under higher pressures. Diesel engines also don’t rev as high as petrol engines, as their peak torque anyway develops at much lower rpms. These are compression ignition engines and don’t have spark plugs. As they are low revving they also have lower friction in comparison to a petrol engine, which therefore increases their lifespan if maintained well.

Typically, diesel engines have nearly twice the life-span of a petrol engine if routine maintenance is followed. This maintenance, however, can be slightly more expensive than a comparable petrol. If you maintain a diesel engine well and drive carefully, it can last 400,000 km before needing a major engine overhaul. Also read: Average life of a diesel engine in India

#2 Maintenance costs of a diesel engine

Diesel engines these days are precision engineered common-rail diesel engines, who don’t ask for higher maintenance costs compared to a petrol engine. However, there are some parts and components that are a lot more expensive. The fuel filter for one. An average fuel filter for a small petrol car costs between Rs. 200 to Rs. 500. For a diesel car, it can be anywhere between Rs. 1,800 – Rs. 3000, and needs replacement every 15,000-20,000 km. Oil changes also need to be more closely monitored in a diesel engine, and then there are parts like engine mounts than need inspection more often. Also read: Diesel engine maintenance tips

#3 Turbo-lag and drivability

One big concern buyers of diesel cars have is “turbo lag”. Turbo lag is the jargon used to describe the reaction time from when you press the accelerator to the time the car actually surges ahead. This lag usually comes in diesel cars that have large turbochargers to develop more torque, but this peak torque only comes in when the engine revolutions per minute (RPM) is around 2000 rpm or so. Drivers of diesel cars need to adapt their driving style, so as to keep the car in the “power band” where peak torque is developing. This means you will have to downshift gears more often than you would in a petrol car and upshift quicker as well. Also read: Diesel cars with turbo lag, is it a deal breaker?

#4 Resale value of diesel cars

With the kind of demand diesel cars are seeing now, the resale value of diesel cars has also gone up. For instance, the petrol Ford Figo has very poor demand in the resale market and buyers can pick one up for as little as Rs. 3 lakh, while the diesel Figo has prices of over Rs. 4 lakh even in the second-hand market for a car that has done a significant mileage. In the case of the Maruti Swift too, the diesel fetches much better resale value these days compared to the petrol, even though the petrol is a very popular car on the second-hand market. As long as the differential in fuel prices and the demand for new diesel cars surges, the resale value too will remain high. Also read: Which is the more environment friendly fuel?  

#5 Noise, vibration and harshness

Modern diesel engines are quite refined, but they will never be as quiet as a petrol engine. One of the biggest reasons for diesel engines being noisy is that they run on high compression and the fuel molecules in diesel fuel is much larger than petrol – hence producing more noise while the fuel ignites. Also as there’s no spark ignition in a diesel engine and the fuel self-ignites due to the heat generated during compression, it clatters when cold. Even the best sound dampening in the car will allow some noise and vibration to filter through. It’s not uncomfortable, but it’s something you have to get used to if you drive a diesel car. Also read: How to reduce noise of diesel cars?

Share any other concerns you have on diesel cars with the CarToq community and we’ll see how best they can be addressed.