What new (used) car to get? Diesel or petrol?

My petrol car left me down prematurely for some manufacturing issue in the engine so I need to buy a new (of course used) one. Ideally I would buy electric but I’ll wait a couple more years as I have the impression that more and better models will come out soon. I am also not considering hybrid for the moment.

In the past I chose petrol because its exhausts fumes are supposedly less harmful for human health and some cities had started banning diesel car from entering their centres.

But now I have understood that Diesel engines consume less fuel and produce less CO2, so, given that I drive 99% of the time outside the city, I am considering changing.

What do you think?


I was also wondering about this. Our VW Polo (2004, 1.9L TDI, 100PS, Diesel, 4.5L/100km) will surpass the 300’000km mark by end of this year. Next MFK is in around 10 months and we’ll need a new car by then.

What are mustachian/frugal used cars? I guess they should be in the 5-10k price range?

On this part I have to disagree, in general, Diesel and Petrol have the same CO2 emissions for the same weight and power (efficiency of motors are pretty similar, your individual driving style is much more important). What makes people thing a Diesel consume less is because we buy L at the gas station instead of kg. Diesel is more dense (energy and kg/L) than petrol. Modern Diesel are pretty equivalent on other pollutants now (NOX etc.), so it does not change much.
Think of it, you need a certain amount of energy to move a certain mass, and you are burning C-H links to gain ths energy. The energy gained by C-H link burned is the same, regardless if it is Diesel or Petrol.

Skoda Fabia could be a choice. New ones are already at around 15k, so used ones (1y) could be in that range. Size wise it would be also equivalent.

Efficiency plays a key role, and diesel engines are about 25% more efficient, hence the lower consumption. The rest of the stuff goes into warming the outside air around the car.

My argument against diesels is that they stink bad, even new. But this is very subjective.

What is less subjective is that once a diesel car is out of warranty it’s basically a ticking timebomb for the turbos to go flop and require a huge bill for repair, which is an economical disaster for a small car.

If you want reliability, go with a naturally aspirated petrol engine, Mazdas and older Hondas are a good example. VAG concern has banished most turbo-less petrol engines for awhile now, but you might find something in Skoda on the lower end (1.4-1.6i) without a TSI.

1 Like

Look, I am a total noob, but I see on autoscout24 that Diesel engines consume less fuel and produce less CO2 than the corresponding (in terms of power) petrol engines. Eg, for a Skoda Octavia from 2014:

Diesel 1.6L (105 PS):

Total: 4.0 l/100 km
Stadt: 4.8 l/100 km
Land: 3.6 l/100 km
104 g/km

Petrol 1.2L (105 PS)

Total: 5.1 l/100 km
Stadt: 6.0 l/100 km
Land: 4.5 l/100 km
117 g/km

Though TBH I am surprised to find that the equivalent to a 1.6L diesel is a 1.2L petrol engine, I was expecting at least an 1.4L…

Would that be MPI instead of TSI? Seems rare on autoscout24 (non-existent for an octavia, actually)

You cannot compare a L of Diesel and a L of petrol, since the amount of carbon in both of these are different, better to compare kg are actually.

For instance you can see that a petrol consumes nearly 28% more fuel on the total cycle, however, it emits 13% more CO2 than a Diesel. That is basically the difference in energy density. From these numbers I however agree that petrol has still some catch up to do.

But in the end I buy litres at the gas station, no?

Yes, so in absolute terms the diesel is better, climate-crisis-wise, no?

a Prius is better.

  • the hybrid drivetrain did not have any major issue in the last 15-something years
  • you can drive pure EV (albeit, only for a limited time and with slow acceleration)
  • has a naturally aspirated ICE engine built in for eternity

It doesn’t come in the 5-10k range, though.

I might probably have to change/add a car next year and I have the same impression. Hybrid are still very expensive for what it is. I don’t know if the potential fuel economy really upset the steep entry price?

A Prius is too small for me. I looked at a Corolla and an Auris but they do cost significantly more and don’t consume SO much less.

Also, what I never liked with hybrid cars is that suddenly you have two systems that can break (though I know, Toyota is very reliable). I want to go full electric but I decided to wait a couple more years (ideally my old car would have lasted that long…) as the cars which would fit my family still cost a huge amount and the range is not what I would like to have.

Recommend as well what user137 said. Japanese cars are good. Simple and reliable. German and other manufacturers have 2 main drawbacks: 1) use of turbos. Look / sound fancy but basically means a smaller engine than otherwise and pumped more = more likely to break / have problems 2) electronics. German companies love to add lots of electronics to the car. Guess what? Easier again to have problems.

You are a real mustachian, go for Japanese or similar


Well, not sure it’d be a “mustachian” thing to do to spend a few Ks more. But I would totally prefer a car without turbo. Only the family got used to the space offered by the Octavia so I guess we’ll get another one of those (just avoiding the TSI engines with the oil leak problem).

Probably the best thing to do would be to wait a bit, because prices are higher than usual due to the chip shortage and whatnot. But then I’d need to rent a car (at least) for the xmas and sport holidays and that’d be already around 1000chf.

1 Like

Very happy with our old diesel octavia. Over 300k. Great car

If you stay out of cities, then I’d say that the new EURO 6b Diesel engines are certainly a good choice.

That’s a prejudice. I had a Japanese car myself and it was not a good experience. Stuff was breaking all the time.

Another prejudice. Saab also had turbochargers and they still did hundreds of thousands of kilometers.

I disagree.

I’d do this:

  1. Get a yearly magazine like the Autobild TÜV-Report and look what model in your price range is best in the statistics. It might not necessarily be a Japanese brand.
  2. Make sure the car has been taken care of. For me, that’s the main thing to make a car reliable.

I guess you can get unlucky with almost every car. But I also get the impression that with Japanese cars you’re generally on the safe side. I had a few Japanese cars and currently I drive a Japanese SUV, I didn’t have any issues so far.

We have a Mar 2016 Honda Civic Tourer (Kombi) - Petrol, automatic, approx. 50 K kms on the clock.
Happy with it so far and there has been no problem at all (touch wood).

No prejudice at all. Just evidence

4 out of top 5 most reliable cars are either Japanese or Korean. Same type - no turbo, natural aspirated and simple. Across 15 categories.

Same here What Are the Most Reliable Cars?

Another here. Mostly Japanese and Korean cars. The most reliable car brands in 2021 - and the least | What Car?


new plan :slight_smile:

The AMAG leasing calculator is apparently faulty. On some combinations you can get a brand new A6 on 3-400CHF a month with virtually zero money down (1-2000CHF). The resulting contract WILL get signed nevertheless. 5k a year might be too much for a mustachian, but you get to have a new or an “almost new” Jahreswaren for peanuts. Then you can give it back 2 yrs later.

I’ll let you play with the numbers :slight_smile:


Again I can recommend a Prius+. When I need even more space I disassemble the 2 foldable back seat (just 5 screw) and I built a custom wood based and I get a cavernous space behind.
The Prius+ itself is preety much unbreakable - I was in Zurich Saturday night and the feeling was that 80% of Tax and Uber were actually Prius+ :smiley:
They are out of your price range. Actually since Toyota stopped producing them and the microchip crisis hit, I could sell my second-hand one fora profit per autoscout24 prices.

The problem with old diesel car is that they cheat. I have worked for the development of diesel engines software. They always have a certain calibration map when they recognize a testbench and another one on the road. They caught some of them but this kind of cheating has always been there. So yes you get that fuel consumption, but the amount of shit that actually comes out of the tailpipe (NOx, pm etc) is much more than what was tested.

Newer diesel do not suffer from this. They are more honest. But they are out of your price range as well.

For this reason I would suggest a naturally aspirated petrol engine. A KIA ceed sportswagon (the korean octava combi basically) may make a good choice. 7 year warranty as well.

By reading and partipating to this forum, you confirm you have read and agree with the disclaimer presented on http://www.mustachianpost.com/
En lisant et participant à ce forum, vous confirmez avoir lu et être d'accord avec l'avis de dégagement de responsabilité présenté sur http://www.mustachianpost.com/fr/