Diesel vs Petrol?

getmore4less

If you have dealer with a selection in your price range with the engines you want to try go have a chat discuss the pros, cons of each and the specs.

chances are they suggest trying them.

once you know what spec, engine color gearbox you want you can narrow down then wait for the right one. not familiar with which toys are standard and which have to be added on the Audi range but it is a good idea to familiarise with optional extras.

Some people hate the DSG, some hate the TDI, I like both.

Some reports on the new smaller petrols in the Skodas are mixed on their flexability and acheavable MPG. some say they are better with the DSG when you don't have to stir the gears yourself.

andygb

getmore4less wrote: »

wonder whats wrong with this one

http://www.autotrader.co.uk/classified/advert/201302135323031

That is a very cheap car on the face of it. It does have a short MOT, so I wonder if the DPF has gone and possibly the DMF. If that was the case then it would cost around £1100 to fix them, and then you have the possible gearbox problems.
A quick test drive by an experienced car person would highlight any glaring problems.

getmore4less

another one that looks on the cheap side

http://www.autotrader.co.uk/classified/advert/201302135325438/sort/default/usedcars/price-to/7000/price-from/5000/maximum-age/up_to_4_years_old/maximum-mileage/up_to_40000_miles/model/a3/make/audi/onesearchad/used/onesearchad/nearlynew/onesearchad/new/radius/1500/page/1?logcode=p

Indout96

I have the VW Passat 2.0 TDI (140bhp) so same engine as the Audi and drive lots of short trips. 3.5 miles to work ect. I have around 1 longer trip around every month of around 160 miles and that seems to keep the DPF OK ( a bit more often in summer)
In this weather going to work it returns mid 30's average there and back, in summer this was mid 40's. on longer trips around 50mpg average with motorways around 60mpg at steady 70.

Tax is £170 per year, I have the renewal in front of me now.

I bought it as I was going to do silly millage for work but then my job changed and thats now not happening. But I am now a diesel convert.

One thing to keep in mind buying second hand is that a lot of these will be ex company cars and around 80,000 miles, there is a reason they move them on at that time (we do at work as well) so keep a bit back for any parts that may be on their last legs. My Turbo actuator went after 4 weeks but since then its been perfect

redux

A petrol engine has to be run rich on fuel until warmed up - like the choke being used on old carburettor engines - whereas a diesel doesn't have a choke system to run rich.

On top of that the catalyst system doesn't start to work properly until hot, so for short distances from cold a petrol fuelled car is actually causing much higher harmful emissions than a diesel.

So I don't agree with the assertion that short trips make a diesel a worse option.

andygb

redux wrote: »

A petrol engine has to be run rich on fuel until warmed up - like the choke being used on old carburettor engines - whereas a diesel doesn't have a choke system to run rich.

On top of that the catalyst system doesn't start to work properly until hot, so for short distances from cold a petrol fuelled car is actually causing much higher harmful emissions than a diesel.

So I don't agree with the assertion that short trips make a diesel a worse option.

Neither do all the taxi drivers in the UK, and they drive for a living:)

mike_the_bike_2

If you are going for an 06/07 ish VAG group car i'd go for the 1.9 TDI PD engine as fitted in various Skodas and Golfs and possibly Audi's??? Bit noisy on tickover but no DPF filter to get blocked or go wrong and extremely economical and they do phenomal mileages reliably

GolfBravo

redux wrote: »

A petrol engine has to be run rich on fuel until warmed up - like the choke being used on old carburettor engines - whereas a diesel doesn't have a choke system to run rich.

Diesel engines take much longer to reach full operating temperature - in other words, the diesel combustion environment is too cold for complete/efficient combustion. Once the diesel engine reaches its full operating temperature it is way more efficient than a petrol powered engine.

On top of that you have the winter diesel mix making things worse.

redux wrote: »

On top of that the catalyst system doesn't start to work properly until hot, so for short distances from cold a petrol fuelled car is actually causing much higher harmful emissions than a diesel.

Yes, diesel engines are "better for the environment", but they are quite deadly for human beings. Ever heard of PM2.5's? This is why modern diesel cars have DPFs fitted. The list of diesel's harmful health effects is quite extensive.

redux wrote: »

So I don't agree with the assertion that short trips make a diesel a worse option.

It isn't about the short trips that kill DPFs and diesel fuel economy, it is the lack of optimum operating temperature. For example, diesel taxis are running most of the day so the engine is always warm. On the other hand, 2 daily short 5 minute trips, eg. to and from work, will never allow a diesel engine to reach the optimum operating temperature for good fuel efficiency, and the DPF will have no chance to regenerate.

Johnmcl7

Bear in mind that not all the 2.0 TDI engines have DPF's, I'm not sure how the engines were used in Audis but for the Octavias the standard 2.0 TDI PD140 engine did not have a DPF, the 2.0 TDI PD140 PD 8v engine in the four wheel drive Octavias did (fairly rare) and the 2.0 TDI PD170 engine used in the VRS did have a DPF. The newer commonrail (CR) versions of the 2.0 TDI's all have DPF's both in the lower and higher power outputs.

In the Octavias, the changeover from the PD to the CR engines was around 2008 so I assume it's probably a similar time for the A3's.

John

gord115

Having had 2 cars with the 1.9tdi engine(around 43mpg) and 2 cars with the 2.0T engine (around 30mpg), I'd say go for the petrol.

Way better to drive,much faster,even when the diesel is remapped.

And they warm up much quicker.