I expected a lot of replies disagreeing with me but this one was totally unextpected!JRobinson wrote:...
Can I assume it's the new car, or that you're a driving instructor - surely you must have a better knowledge of cars than me but I would have assumed (or at least I was taught this when I learnt to drive) - that at 20mph you should probably be in 2nd gear, not 3rd - in which case your revs would be higher than doing 20mph in 3rd gear. How you them manage to be in 5th gear by the time your doing 30 is beyond me - 5th gear is, imo, there for when travelling at the highest speeds, motorways and dual carriageways only. surely it's just as bad for the engine to be running at too high revs than too low revs. Maybe your new car is designed to run better in higher gears at lower speads I don't know.
Yes I do have a knowledge of how cars work, as should be expected with my profession, but I have to confess I'm not sure I totally understand what you are saying.
That is correct the engine revs would be higher in 2nd gear than in 3rd gear and so more fuel would be used in 2nd gear than in 3rd gear. So surely it is a good thing to be in the higher gear. A lower fuel consumption saves money and helps avoid pollution!JRobinson wrote:...at 20mph you should probably be in 2nd gear, not 3rd - in which case your revs would be higher than doing 20mph in 3rd gear".
All cars are now made to be capable of doing lower speeds in the higher gears for this reason and it is now acceptable to block change up the gears as well as down on the driving test since they brought the 'eco' driving aspects into the test.
My car will actually pull up Westwood Hill with the speed limiter set at 30 from 26mph to 30mph in 5th gear.
In that situation I use 4th gear instead but on a flat road a higher gear is almost always more efficient because you need almost no load on the engine.
In older cars 30mph in 4th gear uses roughly a third less fuel than 30mph in 3rd gear on a flat road and with the new cars capable of being driven in higher gears at low speeds the fuel efficiency is even greater.
My car actually tells me when to change up! As I'm coming up Westwood Hill in 4th gear doing 30mph it is asking me to select 5th gear and it suggested 6th gear the other day to one of my pupils doing 40mph in 4th gear on a slightly uphill section of the A21. I instructed her to select 5th gear instead. I will be on to Mazda to find out how useful these suggestions are. I know that the computer must know the speed and the revs but I'm not convinced it realises how steep the incline of the road may be.
Very happy to say that far less fuel was needed for my recent holiday in Shropshire than would have been required in my other car, a 2003 Yaris T Sport, despite the new car being heavier and both having a 1500cc engine
As I mentioned the speed limiter, which virtually all new cars now come with, and which is something I teach my learner drivers to use, I would add that this is where further danger arises when doing 20mph on a road as wide as Sydenham Hill. As the driver needs no attention whatsoever to prevent the vehicle from going over 20mph it is very easy for the attention to wander! This may come to little consequence if the other drivers on the road are sticking to the speed limit and pedestrians stick to the pedestrian crossings in order to cross the road but neither is often the case.
On the other hand the display unit that links to my mobile as soon as I enter the car means that I never need to pull over to make or receive a call. Calls can be made or answered via buttons on the steering wheel with no risk of needing to have my attention anywhere other than on the road ahead and it even reads out any text messages I receive
I am VERY happy with 'Black Betty'