# Why do people buy diesel cars? **URL:** \ **Category:** Factual Questions\ **Created:** [August 16, 2005, 5:52pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299 "2005-08-16T17:52:26Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [August 16, 2005, 10:55pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/21 "2005-08-16T22:55:59Z")
Diesels have one huge advantage for off-road travel in that they are effectively submersible. Because minimal electrics they can be driven through water without needing to worry about splash shorting the system and stalling them midstream. With the attachment of a snorkel to the air intake a properly constructed 4x4 deisel can be driven in water that literally covers the engine with a little care and a few minutes work. ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [August 17, 2005, 12:12pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/22 "2005-08-17T12:12:37Z")
> [@InvisibleWombat](#): > > If you’re talking about the difference between 28mpg and 45mpg, that’s pretty significant. Around here, diesel costs about 8% more than gasoline, so if you can improve your mileage by 60%, you’re coming out way ahead. I could put up with some stench and noise to cut my fuel costs by a third. Oh yeah, the mileage difference was very significant. The only reasons I didn’t buy the TDI were that it didn’t come in standard transmission and the relative scarcity of diesel pumps. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [August 17, 2005, 12:26pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/23 "2005-08-17T12:26:00Z")
> [@Maus Magill](#): > > … the relative scarcity of diesel pumps. Rarely much of a problem. Diesel fuel will be found wherever trucks operate, and diesel cars tend to have impressive range. ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [August 17, 2005, 12:40pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/24 "2005-08-17T12:40:37Z")
> [@Rayne Man](#): > > The modern generation of European diesel engines ( such as the Peugeot Citroën HDI models) and are very clean and almost indistinguishable from petrol cars. The acceleration and low noise levels means that they are on par with non diesel cars. And , of course you get better fuel consumption I was thinking a European would chime in with these points and I second them all (maybe not so much the noise) and would add the durability of the engines too. My Dad’s Saab 9-3 will happily out perform any car he’s had in the past, MPG, 0-60 or the all important 50-70 for overtaking. You’re probably right, with the low cost of petrol (gasoline) in the US it doesn’t pay to make the same investments in diesel engines that pretty much all the major European manufacturers have made. The VW group, Peugeot/Citroen, Renault, Mercedes-Benz, BMW, Fiat all make powerful, reliable diesels that feature strongly in their cars. Try finding a petrol Peugeot 306 with a small engine like my Mum did, not easy 😉 ---
**Author:** ![Mollie\_Magill](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mollie_magill/32/20882_2.png) [@Mollie\_Magill](https://boards.straightdope.com/u/Mollie_Magill)\ **Post date:** [August 17, 2005, 12:59pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/25 "2005-08-17T12:59:01Z")
> [@Xema](#): > > Rarely much of a problem. Diesel fuel will be found wherever trucks operate, and diesel cars tend to have impressive range. That should have been read as “perceived rarity of diesel pumps by one of the two people who would be paying for the new car.” ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [August 18, 2005, 8:34am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/26 "2005-08-18T08:34:43Z")
I used to have a 1.9l diesel Peugeot 205. Not powerful but enough torque to take off like a startled rabbit. ---
**Author:** ![BwanaBob](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bwanabob/32/2985_2.png) [@BwanaBob](https://boards.straightdope.com/u/BwanaBob)\ **Post date:** [August 18, 2005, 11:55am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/27 "2005-08-18T11:55:37Z")
I must be the odd-one out here. I feel that diesel exhaust smells much better than the exhaust of regular gasoline. ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [August 18, 2005, 1:47pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/28 "2005-08-18T13:47:55Z")
> [@BwanaBob](#): > > I must be the odd-one out here. > > I feel that diesel exhaust smells much better than the exhaust of regular gasoline. You really shouldn’t be able to smell the exhaust of a properly tuned, warmed-up gas car unless you’re within three feet of the tailpipe. ---
**Author:** ![slaphead](https://avatars.discourse-cdn.com/v4/letter/s/e9bcb4/32.png) [@slaphead](https://boards.straightdope.com/u/slaphead)\ **Post date:** [August 18, 2005, 3:00pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/29 "2005-08-18T15:00:37Z")
The title of the OP should really be ‘why do people buy diesel cars and then not give them the minimal maintenance they need to be non-smelly and non-noisy?’ Or am I oversimplifying? ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [August 19, 2005, 1:12am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/30 "2005-08-19T01:12:08Z")
> [@slaphead](#): > > The title of the OP should really be ‘why do people buy diesel cars and then not give them the minimal maintenance they need to be non-smelly and non-noisy?’ Or am I oversimplifying? You’re oversimplifying. I wanted to know (a) why people would buy smelly, noisy cars and (b) what advantages they had when diesel fuel is more expensive than gasoline, diesel cars are more expensive than gasoline cars, and diesel cars don’t start well in very cold weather. Several people have responded that, as you said, (a) can be fixed by maintenance. I don’t know if that’s true, but if it is, then I feel a lot of diesel owners are being really obnoxious by not fixing their vehicles. Your oversimplified summation didn’t address (b) at all, although a lot of the other people in this thread have at least addressed the cost issues. When I bought my last truck, I was willing to consider a diesel for the towing power and torque. It was 20 below zero when I went shopping, and the Ford dealer couldn’t get either of his diesel trucks to start. That pretty much killed the idea for me. It may not get that cold too often but when it does, not having your car start could be life-threatening out here in the country. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [August 19, 2005, 2:21am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/31 "2005-08-19T02:21:13Z")
I have a 23-year old diesel car, and I haven’t noticed any smell, even when I walk around the car with the engine running. (No I haven’t gotten used to it, I just got it a couple weeks ago.) It _is_ noisy, but does that really bother you? ---
**Author:** ![Schuyler](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Schuyler](https://boards.straightdope.com/u/Schuyler)\ **Post date:** [August 19, 2005, 2:28am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/32 "2005-08-19T02:28:09Z")
Diesel engines (compression ignition) have a higher theoretical efficiency than Otto-cycle engines (spark ignition), since their achievable compression ratio is so much greater (figure 20:1 for Diesel vs. 10-14:1 for gas); this could translate into an increase in thermodynamic efficiency from 20-25% for gas up to maybe 40% for Diesel. For a specific output, they are heavier, which is a down-side, but they also tend to be more reliable due to that same heavier construction. So, these engines rule for mileage and longevity, which is why long-haul trucks and big stationary generators would tend to be Diesel, but they aren’t so good for power/weight or power/$-of-initial-cost, which is why they don’t sell so well in U.S. cars - that changes in countries in which the dynamic of fuel costs is different than it is in the U.S. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [August 19, 2005, 4:18am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/33 "2005-08-19T04:18:59Z")
> [@gotpasswords](#): > > \*\*Colibri \*\* - Diesel’s gotten significantly more expensive than gas. D’s going for anywhere from $2.99 to 3.19 a gallon. Price range for 87 octane gas is in the $2.69-2.89 range. That’s very interesting. I just checked prices here and diesel is $2.06 and 92 octane gas about $2.45. That’s US gallons per US dollars. This is quite odd since gas prices in Panama have typically been around 20-30% more expensive than in the US. Pardon the small hijack, but what are the factors that caused diesel’s price to go up so much relative to gas in the US? ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 19, 2005, 4:27am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/34 "2005-08-19T04:27:46Z")
> [@Colibri](#): > > Pardon the small hijack, but what are the factors that caused diesel’s price to go up so much relative to gas in the US? The usual excuse is that demand increases in the winter because so many houses are still heated with oil. The pattern I’ve noticed is that diesel costs more than gasoline in the winter, and less in the summer. This is the first year I’ve noticed diesel staying more expensive than gasoline in the summer. ---
**Author:** ![Rayne\_Man](https://avatars.discourse-cdn.com/v4/letter/r/df705f/32.png) [@Rayne\_Man](https://boards.straightdope.com/u/Rayne_Man)\ **Post date:** [August 19, 2005, 6:23am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/35 "2005-08-19T06:23:55Z")
The price of diesel has also risen relative to that of petrol in the UK. The reason given is that more and more people are buying diesel cars . A few years ago only 10% of cars used this fuel , now it is nearer 50% and no new diesel refineries have been built for years to cope with this demand. We also get a price rise every winter due to the extra demand for heating oil. I bought my first diesel car back in 1984 ( Peugeot 205 ) . It was such a rare thing then, that a couple of times people came up to me in filling stations and said to me “you do know you have just put diesel in that car” . The funny thing was that they always waited for me to finish the process before they pointed out my “mistake” ---
**Author:** ![zagloba](https://avatars.discourse-cdn.com/v4/letter/z/977dab/32.png) [@zagloba](https://boards.straightdope.com/u/zagloba)\ **Post date:** [August 19, 2005, 8:30am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/36 "2005-08-19T08:30:29Z")
In past years, diesel in the US was almost always no more expensive than regular gas on a per gallon basis, and often sigificantly cheaper. As noted above, currently it’s at least 3-5% higher than premium at least in the Bay Area, which has truckers complaining rather loudly. I’ve been wondering about the causes of this price inversion. We don’t have the high performance diesel engines here in the US that are so common in Europe even in luxury brands like Audi and BMW. One reason is that diesel here is much higher in sulfur. We can thank the trucking lobby for that. Reducing the sulfur level would increase prices by a few cents per gallon, but would also allow higher performance car engines without increased emissions. One development that makes newer diesels less noisy and noisome that before is the advent of direct injection, where the fuel is injected directly into the cylinder rather than into the intake manifold upstream of the intake valve. This of course requires the fuel to be delivered at much higher pressures, but allows much tighter control of the timing and amount of fuel delivery. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [August 19, 2005, 11:59am UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/37 "2005-08-19T11:59:11Z")
> [@Schuyler](#): > > For a specific output, they are heavier, which is a down-side, but they also tend to be more reliable due to that same heavier construction. A gas engine’s basic needs are fuel and spark. A diesel engine’s basic need is fuel. Less complexity = more reliability. Particularly when one of the complexities that you are doing away with is electrics, which are notoriously unreliable. ---
**Author:** ![Gary\_Robson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gary_robson/32/3448_2.png) [@Gary\_Robson](https://boards.straightdope.com/u/Gary_Robson)\ **Post date:** [August 19, 2005, 2:03pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/38 "2005-08-19T14:03:14Z")
> [@Colibri](#): > > That’s very interesting. I just checked prices here and diesel is $2.06 and 92 octane gas about $2.45. We’re at a higher altitude here, so few of the stations around here even _have_ 92 octane. “Regular” here is 85.5 and “Premium” is generally 89. As of a couple of days ago, regular was $2.45 and diesel was $2.65. I didn’t check premium prices, as I tend to avoid vehicles that require premium gas. Why pay more for gas than you have to? ---
**Author:** ![irishgirl](https://avatars.discourse-cdn.com/v4/letter/i/8edcca/32.png) [@irishgirl](https://boards.straightdope.com/u/irishgirl)\ **Post date:** [August 19, 2005, 5:25pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/39 "2005-08-19T17:25:37Z")
In the UK at least, diesel cars are also cheaper to insure. So basically, they’re for the thrify people who don’t mind if they can’t go very fast. ---
**Author:** ![Schuyler](https://avatars.discourse-cdn.com/v4/letter/s/54ee81/32.png) [@Schuyler](https://boards.straightdope.com/u/Schuyler)\ **Post date:** [August 19, 2005, 5:41pm UTC](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299/40 "2005-08-19T17:41:28Z")
> [@zagloba](#): > > One development that makes newer diesels less noisy and noisome that before is the advent of direct injection, where the fuel is injected directly into the cylinder rather than into the intake manifold upstream of the intake valve. This of course requires the fuel to be delivered at much higher pressures, but allows much tighter control of the timing and amount of fuel delivery. Hope that this is not out of turn: Diesel engines are compression ignition, which means that after suitable temperatures are reached in the combusion chamber due to adiabatic compression of air only, then the fuel is directly injected whereup self-ignition occurs. This is in contrast to a spark ignition engine, in which the fuel-air mixture is compressed and then a spark initiates combustion; over-heating, hot-spots, or low-quality (low octane) gasoline may cause a gas engine to knock, which is violent combustion of the fuel-air mixture rather than an orderly burn initiated by the spark plug; dieseling can also happen after shut-down, where there is no spark but enough residual heat in the engine to maintain self-ignition. So in that sense, diesel engines are by definition direct injection; it is the new application of in-cylinder injection, rather than port or manifold injection, that is the recent development for gas engines. Back to the **OP** , but it’s my sense that the primary reason to run a diesel in the U.S. is economy - IIRC (can’t find a link) Car and Driver went cross-country in a diesel volkswagen without stopping for a fill-up; of course, they filled the back of the car with extra tankage and transfered fuel on the go. 😛 [Previous page](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299.md?page=1) [Next page](https://boards.straightdope.com/t/why-do-people-buy-diesel-cars/317299.md?page=3)