Frequent short journeys are bad for car - yes or no?

[sbasak]

Usually it is said that frequent short journeys are bad for cars.

Because -

Battery is not charged enough
Engine lubrication is not proper as engine/oil don't reach optimum temperature
Condensation on exhaust corrodes it quickly

Is this really true? Does it differ between petrol & diesel cars?

What distance/duration is exactly considered a short journey?

[amu1983]

The 2nd and 3rd points make sense to me. A good charging system will quickly (a few seconds) replenish the battery power used up for starting.

There shouldn't be much difference in petrol/diesel engines, and both would get equally affected in such conditions. Diesel, perhaps more because of it's impure nature and higher SO2/NO2 content in the exhaust.

A trip will be termed as 'short', if the time for which the engine is kept running is 'short'. Under normal conditions, an engine reaches its optimum temperature in 2-3 minutes. Might take something like 5 mins in winter.

[autoenthusiast]

Yes frequent short trips increase wear and tear in an enginer (whether petrol or diesel).

It also increases the fuel consumption of you vehicle, since it does take the engine sometime to reach optimum temperature for your FE.

IMHO, I guess any trips less than 3 - 4 km would be considered short trips. Maybe someone else too can add more to this point.

[sreenivass]

Owner manuals, improving FE tips, etc.. typically seem to quote up to 5 KMs to be short trip.

[amu1983]

It's not the distance... It's the running time for the engine that matters. If you let it idle for a few minutes, and then drive, it'll be alright. You shouldn't rev-up the engine though... just let it idle at lowest possible rpm.

Fortunately, I kinda live on a hill, so when I start off in the morning, I just roll down the hill (in 2nd gear, so that I use engine braking, and no gas), and by the time I reach the main-road, my car is all-set.

[sreenivass]

Originally Posted by amu1983

It's not the distance... It's the running time for the engine that matters. If you let it idle for a few minutes, and then drive, it'll be alright. You shouldn't rev-up the engine though... just let it idle at lowest possible rpm.

Fortunately, I kinda live on a hill, so when I start off in the morning, I just roll down the hill (in 2nd gear, so that I use engine braking, and no gas), and by the time I reach the main-road, my car is all-set.

Well it has to be both distance and time. The transmission system is not used when the car is idling.

Coming to revving up, the suggestion is not to accelerate/ rev up much during the initial few mins or kilometers.

[typeOnegative]

Originally Posted by amu1983

Fortunately, I kinda live on a hill, so when I start off in the morning, I just roll down the hill (in 2nd gear, so that I use engine braking, and no gas), and by the time I reach the main-road, my car is all-set.

What was that? Did not get it. Do you have gas assisted brakes or am I missing something very profound?

[navdeep]

I think anything around 10-12 kms is safe.

[esteem_lover]

Originally Posted by typeOnegative

What was that? Did not get it. Do you have gas assisted brakes or am I missing something very profound?

what if he does have gas assisted brakes, he is not going to waste the gas by using them now, is he ???

[navdeep]

I think he means the resistance provided by lower gears.

[adya33]

I for one don't think short journeys make any difference to engine.
Really thinking about it, well maintained engines last really long.
The only problem I can think of is, lower FE since engine would be cooling when car is switched off & would again require getting warmed once started.


And based on what you would define "short journey" ?
For someone living in city a drive of 3km might take half an hour, so its definitely not a short journey for him. Where as for someone living in small town a journey of 10km might not take more than 15 min.

So how would you define short journeys?

I think he means the resistance provided by lower gears.

Actually on downhill roads you should use maximum practically possible gear without pressing accelerator, as at higher gear the engine will sip less fuel resulting in better FE.

[xinome]

Quote:
I think he means the resistance provided by lower gears.
" Actually on downhill roads you should use maximum practically possible gear without pressing accelerator, as at higher gear the engine will sip less fuel resulting in better FE. "

wow i never knew this i just slide down in neutral applying the brakes,
guess now i found my answer to why my break pads get worn out..

[airfoil]

Originally Posted by amu1983

Fortunately, I kinda live on a hill, so when I start off in the morning, I just roll down the hill (in 2nd gear, so that I use engine braking, and no gas), and by the time I reach the main-road, my car is all-set.

Your loading up the engine before it is warmed up, by rolling downhill in low gear is doing your engine a power of harm - if you're one that believes warm ups are a good idea.

[rohitbagai]

Originally Posted by adya33

Actually on downhill roads you should use maximum practically possible gear without pressing accelerator, as at higher gear the engine will sip less fuel resulting in better FE.

I guess we should be in lower gear as possible. Lower the gear the more will be engine breaking power. Obviously I do not mean 1st gear. It should be 2nd or 3rd max.

Originally Posted by amu1983

Fortunately, I kinda live on a hill, so when I start off in the morning, I just roll down the hill (in 2nd gear, so that I use engine braking, and no gas), and by the time I reach the main-road, my car is all-set.

If you mean you saving fuel then its just opposite. Engine Braking will consume more fuel than if we were accelerating at same speed in same gear. (Especially if its petrol car))

[typeOnegative]

Originally Posted by adya33

Actually on downhill roads you should use maximum practically possible gear without pressing accelerator, as at higher gear the engine will sip less fuel resulting in better FE.

That my friend is extremely dangerous. For two reasons:

1. The car can easily go out of control if there are too many bends and curves.
2. The frequent braking that you have to do will result in over-heating of the braking system thus considerably reducing the braking efficiency. This means you will be in a tight spot on a long slippery slope. Pardon the eloquence.

Also as someone has rightly pointed out, you will be saving on fuel alright, but spending more on your brake pads. Money aside, it is dangerous to do what you are suggesting. Rule of thumb - descend on a gear one step below the gear for ascent. Not valid for auto trannies though.