Differences In Driving Manual Diesel Compared To Manual Petrol?

[furness lass]

I've just bought a brand new RA4 and generally very pleased with it. It's only a 2 litre but it feels very nippy and pulls away sharpish. Previous car was a 53 reg rav4 petrol and still own and love a 14 year old Celica.

Bit embarrassing this, but after 25 years driving petrol without any problems I have stalled this new car a few times while driving, eg a few times going on a roundabout , approaching a red light and when turning left. ( no problems with starting or getting the bite for hill starts)

I know it's something I'm doing but not sure what!!

What do I need to be more aware of? What is the difference between driving a diesel and petrol?

The clutch feels different, I have to move my foot down farther. I have noticed the revs are a lot different and the gear changing needs to be a lot more precise than my very forgiving Celica which would go round a corner in 5th without complaint ( if I was daft enough to do it)

I know it's a matter of time to get used to it but any tips please? I'm scared of stalling it in busy traffic.

[Uncle Buck]

Welcome to the forum Kathleen :)

As you pointed out yourself, there are certain differences between the way petrol & diesel engines deliver their performance. In a petrol model you tend to use medium revs to change gear & cruise along, whereas most larger diesels deliver their best pulling power at lower revs & are able to cruise at less than 2000 rpm. But petrol engines can be much more forgiving & allow you fewer gear changes because they have a wider operating range. Diesels & even petrol-turbo engines can 'bog down' at very low revs, hence the need to to keep them in the 'zone' where they are happiest. 'Bog-down' simply means the turbo isn't spinning fast enough to respond to the amount of throttle you're asking for.

When it comes to overtaking you might be used to dropping a gear or two even in the petrol car, but may find you don't need to in the diesel. So, in short, petrols like to rev & diesels not so much. That's why you'll find the red line at the top of a diesels rev counter might be as low as 4500 rpm - compared to a petrol's 6500 rpm.

Hope that helps a little - feel free to ask if I've missed anything !

[Cyker]

Blimey, I must admit I'm surprised you're stalling it so easily!

I have the opposite problem; I can drive my Yaris D4D almost everywhere in 4th if I want to from 20mph to 50mph, and can easily move off in 1st with just the clutch, but when I had an Aygo as a courtasy car I was stalling the thing all the time until I drilled into my brain to use more accelerator when shifting and moving off

[furness lass]

Hi Paul, Thanks for the reply. . I wish I was more technically minded. Generally I've no problem with gear changing. The ' shift up/down ' light was initially very helpful. And I have noticed the rev counter is different.

Can I ask a bit more about this ' bogging down'. You say the 'turbo isn't spinning fast enough to respond to the throttle' ......what does that mean I should be doing..? Was I reving too much as I came on to the roundabout..or not enough? .too quick a gear change? Changing gear at the wrong time?

Needless to say I'm not doing this every time! Generally no problems but I like to understand how and why when its not right.

I appreciate you taking time to answer. :)

[Uncle Buck]

From what you've described in your initial post, it sounds as if you're leaving it a bit too late to change down to a lower gear. So the revs drop right down to below 'normal' idling revs & the engine then stalls. Many of us have adopted a 'block' change pattern - this means instead of just changing up or down one gear at a time, you might choose to go from 4th to 2nd to take a slow turn (after braking) or accelerate a bit harder in 3rd (out of a roundabout for example) and then change straight into 5th. You may already be doing this, but if not it might be worth a try to see how it feels.

Modern turbo-diesels need a bit of adjusting to, especially after a few years of petrol engines. A bit of time & experimentation can bring satisfying results - smoother progress, better fuel economy, etc. :)

[Cyker]

The D4D's are generally strongest between 2000 and 3000 rpm, but most efficient cruising below 2000rpm. I tend to drive my Yaris D4D between 1500 and 2200rpm and get good oomph but also decent mileage.

What gear where you changing from and to when you stalled on the roundabout out of curiosity?

Mini roundabouts I'll usually cross in 2nd, bigger ones in 3rd or 4th depending on how big.

The 2.0 D4D in my brother's Corolla (Before he wrote it off:crybaby:) seemed to follow the 1st up to 10mph, 2nd up to 20mph, 3rd up to 30mph etc. thing as a general rule of thumb.

The RAV4 is a lot heavier tho' so I'm not sure how much difference that makes...


Don't worry tho', all new cars take a bit of getting used to. I'm sure you'll be fine once you get settled into it :)

(If it helps, I nearly shat myself when I first drove my Yaris; Revved it up to 2000rpm to gently move off like I used to in the crappy old Fiesta I traded in and the thing shot off like a rocket

I quickly learned that a) 2000rpm, while okay to move off in a small petrol, is far too high for a diesel, and B) the clutch on the Yaris is MUCH shorter than in a Fiesta so when I thought I was going for the bite point I was actually fully-engaging it!

Ironically I had to unlearn all of that when I was in that Aygo because it needs some higher rpms to avoid stalling when moving off, and the clutch bite is so much higher!)

[furness lass]

Thanks Paul. Think you could well be right about my not changing down too late (not been an issue driving my Celica but that is a very different car to the Rav) But now that you mention it.....

I'll also try your suggestion re block change. I was taught ' old school' so tend to go down the gears. I m doing a couple of reasonably long trips over the next couple of days so it ll give me plenty of opportunity to focus on what I'm doing. I ll keep you posted.

Once again, thanks! :)

[furness lass]

Thanks Cyker. As you say ..it ll take time to get used to it. The gears do seem to relate to 1st to 10 mph 2nd to 20 etc. Not sure what gear I was in as I entered the roundabout. ...certainly I think as Paul suggested not changed down when I should have. I have negotiated lots of roundabouts OK but last night as I was on the roundabout a car shot out in front of me just as I was changing gear I took my foot off the accelerator to brake and stalled . Not the place to do it. Ah well this will help me to focus and concentrate