Second hand diesel car

forgotmyname

marcarm wrote: »

Can I just ask, how often is every now and again?

Looking at our first diesel tomorrow and there will be more a few short journeys but mixed with some longer ones.

Depends on the car, depends on your driving style, depends on your day to day traffic conditions and how clean burning the engine is.

Take 50 identical cars some will need it doing a lot less. Dont skimp on servicing. The manufacturers service limits are limits not targets.

forgotmyname

daveyjp wrote: »

The 50mph in 3rd is an internet myth. All that does is burn more fuel, which creates more soot, which enters the DPF and needs to be burnt off!

The car systems decide when to regenerate the DPF. On my DPF cars it has been every 300-500 miles regardless of how it is driven. Once its starts regenerating you should drive until it stops, a royal pain when it starts just as you are about to reach your destination.

A DPF is a consumable part and replacement can be needed after as little as 40,000 miles, cost is £500+ depending on vehicle.

For short commutes there are plenty of petrol cars which give decent mpg around town.

Not a myth at all, some cars require a certain engine temperature and a certain speed and certain rpm to enter the regen mode. Some will also only fail the regen so many times before the counter needs to be reset.

So many variables and so many systems, owners need to read the handbook s carefully to see whats required.

marcarm

forgotmyname wrote: »

Depends on the car, depends on your driving style, depends on your day to day traffic conditions and how clean burning the engine is.

Take 50 identical cars some will need it doing a lot less. Dont skimp on servicing. The manufacturers service limits are limits not targets.

Thanks, the one we're looking at has a full dealer history, the last being a couple of weeks ago so intend to keep up with the servicing, maybe not at the dealer as we're not planning on selling it on but at our local indie who we have been using for years.

System

daveyjp wrote: »

The 50mph in 3rd is an internet myth. All that does is burn more fuel, which creates more soot, which enters the DPF and needs to be burnt off!

Not a myth and I'm sure that the stage 3 regen on my Euro 6 truck actually kept it in 11th gear instead of 12th.

The idea is that you get the DPF hot enough to burn it off. It DOES NOT CREATE MORE SOOT unless you sit there with your foot hard on the throttle. In fact its likely to create less than being in a higher gear as the engine load is less and you need less throttle.

System

daveyjp wrote: »

Eventually it will fail to regen as the DPF will be full of ash. At that point the same garage will take cash of you to fit a new one.

The ones on the lorries I drove which had over 400,000 miles on were showing 0%-1%. But they didn't do short journeys and each one several times a week would do at least a 400 mile round trip with just one stop.

pd52

Used modern diesel = money pit . Get a petrol

daveyjp

Tarambor wrote: »

Not a myth and I'm sure that the stage 3 regen on my Euro 6 truck actually kept it in 11th gear instead of 12th.

The idea is that you get the DPF hot enough to burn it off. It DOES NOT CREATE MORE SOOT unless you sit there with your foot hard on the throttle. In fact its likely to create less than being in a higher gear as the engine load is less and you need less throttle.

Truck systems are far more sophisticated than the cheap versions fitted to cars.

3rd gear at 50mph is about 3,000 revs, in 6th gear its about 1500. More revs means more fuel burnt, equals more soot.

AnotherJoe

If its frequent short journeys, then a plug in hybrid is probably the way to go.
Diesels will be toxic in a few years time for resale, you can see it coming now, it will be a vicious circle. Unless you plan to drive this until it falls apart like the Blues Bros car, petrol or hybrid.

Richard53

daveyjp wrote: »

3rd gear at 50mph is about 3,000 revs, in 6th gear its about 1500. More revs means more fuel burnt, equals more soot.

My car will descend a long hill in 3rd gear at 3000 revs and use no fuel at all. Fuel burnt is a combination of revs and throttle position - high revs on its own means nothing.


And if it's an internet myth, please someone tell Skoda. The handbook instructions for my wife's car say that when the DPF light comes on, the car should be driven at 2500+ revs in 3rd gear for 5-6 miles (from memory).

macman

What is a 'short commute'? 5 miles, 10 miles, 20 miles? A very rough principle is that you need to do 10K a year to make diesel viable. So tell us the annual mileage.
As for 'diesels have had their day', 4 out of every 10 cars on the road are diesels. And if your statement were true, this would be a good time to buy a used one, as residuals will plummet.
So far, only London has announced an intention to impose an additional tax on diesels, and this applies only to the very old pre-Euro 4 types, of which it is estimated that less than 10,000 cars are likely to be liable for this tax. The majority of diesels on the road are post 2006 and are Euro 4, 5 or 6 and will not be affected.