Which uses more Petrol

Tiesto

Driving around the town in 1st/2nd gear or driving on a motorway at 60 mph
??

Seth Brundle

Driving around town in 1st / 2nd also involves a lot of stopping & starting and the engine revs are going up and down constantly whereas motorway driving would be at a constant 2.5 or 3k revs @ 60mph.
I would therefore assume that motorway driving would be more economical

Redshift

City Driving really guzzles the juice with all the stopping and starting you will get the most miles to the gallon doing a steady 50 mph or there abouts.

padraigmyers

Really depends on the car. On say a city-type car like say a Punto or something like that, driving on the motorway would probably involve drivig at pretty high revs, because its made for city driving, the low gears should be geared pretty low so in something like that city and mororway driving might be much the same, with an optinum speed being around 40-50. However in something like a BMW or equivilant around 80 might be the optinum speed. So it really depends on the car.

However in general urban driving is always heavier on juice then mororway driving, just look at the MPG for any car, they usually give an Urban an Extra-Uuban (motorway) and a combined figure. In some cars these figures will be quite close together (city cars) and in others quite far apart (usually pristige, large cars).

mike65

Obviously town driving is the least economical but as ever your own driving style/abitily will make a huge difference, its possible to trickle round town in thrid gear at 1000 rpm but many esp young folk prefere mad lunges from accelerator to brake and back again
which really annoys the rest of us and just guzzles the gas. As mentoned above gearing can vary alot my 190e is "long-legged"
so its most comfy on the open road (2500rpm at 60) while in town
you might have to use 2nd rather than 3rd in a small buzz box.

Mike

STaN

All depends on the revs. My current 1.4 hovers around 2500 @ 60MPH.

I was driving a 2.5TDI A6 at the weekend and even @ 75MPH it was only at 1500 rpm

mike65

I wish I had 6 foward gears.....in fact all cars should have them.

Mike.

Tazzzie

YES !!!!
6 forward gears !
I have nice honda integra, 1.8vtec and at 72mph i am at 3500 revs. an extra gear 6th would put it at about 1600. Aceleration of course would be ****e, but hey, the speed limit is the speed limit !
and I dont fancy no points just yet....

taz zzi e at ho?mail.com

pclancy

Dont they say when they give the MPG figures for cars that it is based on a speed of 57mph or something? This being the most economical speed for a car? I've driven accross Ireland on the same amount of fuel that I'd use in dublin in a day so long distance is obviously easier on juice. I wonder does every car actually have an optimum economical speed though.

padraigmyers

Well, thats exactly what I was saying above, every car is different. Big Merc's and BMW's are probably hapiest around 80mph, while something like a corsa is probably happiest at around 45-50.

ondafly

Originally posted by Tazzzie
I have nice honda integra, 1.8vtec and at 72mph i am at 3500 revs.

so true ! the good old teg, just wants to keep going in every gear. Fifth gear has astonishing acceleration, and we won't mention fifth gear in VTEC :eek:

Sundy

Originally posted by STaN
All depends on the revs. My current 1.4 hovers around 2500 @ 60MPH.

I was driving a 2.5TDI A6 at the weekend and even @ 75MPH it was only at 1500 rpm

Ah thats cause its a diseal and it has more torque and would be geared differently, i sure some of the tech heads could explain it better.

Ba$tard

Driving around the town in 1st/2nd gear or driving on a motorway at 60 mph

You need to give a metric. i.e. best over time or best over distance. Time, I would say pottering around town (esp in turbo cars). Distance, motorway, obviously enough.

If it was a hybrid car, then most possibly town for both as crusing power comes from petrol in those.



1) a 2.5 TDI 75mph at 1,500rpm? you sure? what year ?

I drove one of those not so long ago and was doing 65mph and was doing 2k. And at that, astonished I was only doing 2k because it makes for the prefect long-haul tourer.


2) Ondafly/Tazzie. I also drive a VTEC (VTi). Honda make the gear ratios in VTEC cars close enough to stay in high-cam mode all the way through the gears and thats why 5th is pretty low ratio compared to other cars.

Also, Honda try to engineer 5th to accomodate the max power of the car at the maximum permissible speed without taking 400 years to get to it.

I know for a fact my car, after driving a buddy's VTi on the Autobahn my car would do more than 133mph if top gear was longer. so, its a more lean towards best acceleration as compared to best top speed in the VTECs.


And yes, hitting VTEC in 5th is a surprise/pleasure
(Or 6th uphill on the autobahn which my buddy did after upgrading from VTi to a new Type-R )

J

Tazzzie

***And yes, hitting VTEC in 5th is a surprise/pleasure
(Or 6th uphill on the autobahn which my buddy did after upgrading from VTi to a new Type-R )***

I had a 1.6Vtec 1991 and now a 1993 1.8Vtec there is a HUGE gearing ratio difference, but christ the speed pick is far better in the 1.8 (possible the 1.6 is a 2 stage Vtec and the 1.8 is a 3 stage??) anyhow the car is a beast! but 6 gears on a type r ????

Honest ???
What year????
I really want one !!!!!!!!!!!!!!!!!

Tazz zie_ hat hurtmail.corn

mike65

Originally posted by Sundy
Ah thats cause its a diseal and it has more torque and would be geared differently, i sure some of the tech heads could explain it better.

Thats about the size of it!. Now if someone can adequately
explain torque...:ninja:

Speaking of which I pulled away cleanly in second at tickover
on the way home (on an upslope) it reminded me of the days when I used to run diesels...the 190 also pulls in 3rd at 1100 without complaint so I'm thinking about loosing some weight and throwing the gearbox out!

Mike.

Ba$tard

Hey Mike65,
That 190, what year? is it the flat-2.0 litre or turbo'ed ? They are a MISER on diesel which is great!

Taz,

The 1.8 Teg's H18C5 are all 2-stage. hence the kick in the face at 5,500rpm

The Type-R was a the new Civic and it was a 2003, 2.0litre 2-stage 200bhp.
He actually sold it about 2 months ago as he could not afford to keep tyres on it Also, beating crazed BMW330i / CLK230Kompressor drivers off the line can make Germans sehr sehr angry !

As for torque v's power.....people have been trying to explain that for eons.

If you can imagine this...car with 2 metal bars attached to 2 highpower sports cars, front and back.

Torque is the feeling of PULL from when the front sportscar accelerates.
Power is the feeling of PUSH from when the rear sportscar accelerates.

Or I could go on and talk about twisting force, energy per area, etc but that will just confuse me and ye

J

Dr. Dre

Originally posted by Sundy, Ah thats cause its a diseal and it has more torque and would be geared differently, i sure some of the tech heads could explain it better.

It's something to do with Diesels pistons compressing it's fuel a lot more than a petrol engine , therefore giving a stronger power stroke.
In a nutshell !

mike65

Originally posted by Ba$tard
Hey Mike65,
That 190, what year? is it the flat-2.0 litre or turbo'ed ? They are a MISER on diesel which is great!

Neither its the 2.0 ltr petrol! Its got tonnes of torque, only 8v of course which helps.

Mike.

Gerry

This is a pretty interesting topic. I'd say the most economical speed is the lowest speed in top gear at which the car is comfortable. Of course it may be fine at 35 or 40 mph in top on a level road, but if you have hills, you are going to have to give it loads of juice to keep going up it at 40, so you'd have to have a higher cruising speed in that case. I'd say the revs would have to be around the peak torque mark, which is around 2000 - 2500 on diesels, and varies wildly on petrols. There are some modern petrols with plenty of low down torque, depends on what cam you have in there and plenty of other things.

Chimaera

Every engine has an economy sweet spot, where the engine is burning the available fuel most effectively. Your most economical speed will be at these revs in top gear.

Economy also depends on the load on the engine - bigger load = more fuel used. Accelerating will load the engine far more than constant speed running.

An interesting way to compare power and torque is to look at the units they are measured in: Torque in Nm and Power in W (Nm/s); power is a function of how the torque varies over time.

Basically, lots of torque means you can haul big loads - this load can be cargo or it can be the load demanded by the acceleration of the car - there is no distinction made of how the vehicle responds to the load.

Lots of power means lots of acceleration - it's an indication of how the engine's torque is deployed in moving the vehicle.