Does weight reduction on a road car make any sense?

old-git

old-git

Moderator
Points
657
Location
Essex
Car
Elan & Robin Hood
I was out walking the dog this morning and I use this time to let the mind wander whilst Dexter is doing his own thing, checking his canine facebook account and replying to messages.

I got to thinking about vehicle weight reduction, no surprise there I guess :) However, I wondered if reducing the weight of your daily driver was actually worth it in terms of improved performance against reduced comfort and practicality? My thinking was thus:

It is generally accepted by drag racers that removing 100lbs (45.45kg) will result in 1/10sec reduction in 1/4mile ET. This would be worthwhile if you were within 1/10 sec of going from a 15 to a 14 sec ET. However, most drivers of cars used for road and track are very rarely able to run consistantly enough to notice 1/10sec improvement.

So, you are now looking at removing at least 200lbs (90kg) in order to achieve 1/5th sec improvement and this could still be difficult to consistantly achieve.

So, how would you remove 200lbs from your road car? Let's take a Honda Civic Si as an example.

Standard - 197bhp/139lbft 2880lbs
1/4 mile 15.56secs@91.19mph

Front seat - 33lbs
Rear seat - 21lbs
Rear belts and brackets - 11lbs
HiFi/speakers - 20lbs
Spare tyre and jack - 34lbs
Floor mats - 5lbs
Boot mat - 3lbs
Headlining - 7lbs
Door cards - 30lbs

Total - 164lbs

Car now weighs 2716lbs
New 1/4 mile - 15.32secs@92.81mph

An improvement of just under 1/4sec which is slightly better than predicted (hardly surprising as performance increase is based on heavier American cars) but doesn't get you anywhere near a 14 second run.

The performance figures are theoretical so will vary dependent on track conditions, tyres, driver skill etc, but the difference between the two figures is sound.

Thoughts? Is this increase in performance worth the work, noise and inconvenience?
 
Last edited:
I havnt previously worried about weight but the Stagea is having a few changes so I will be doing some weight reduction at the same time
roof rails , sound system (4 speakers and a power amp) and maybe the rear seats as nobody has ever used them and I can then fit 5 point harnesses much easier
It wont make a huge difference but on the other hand I dont use the parts that are being removed
 
2% fuel saving and having to sit on the floorpan, steer with a Stilson wrench, can't breathe cos it's 5000 degrees inside.

We all know that right foot technique is the biggest contributor to fuel consumption.

My answer is NO - it's totally pointless
 
old-git said:
100lbs is around 2% fuel saving
Click to expand...

That would save me 37 quid a year on my current mileage. I have no idea how I'd shave 100lbs off though. Actually that's what, 45kg. I suppose I could drive with just 5 litres of fuel in all the time? I might lose a bit of time putting fuel in every morning and evening tho.:):(:toung::confused::lol:

You could get about 20kg off with superlight alloys. They cost a fortune though.
 
I completely stripped my 306. Nothing left but a dash and 2 seats. As much as I like to say it made the car feel quicker, I honestly felt more unsafe. The rear would bounce around awfully and taking corners was.... Interesting.
 
If you are a larger person then losing weight yourself is a good way before even touching the car.
Emptying the boot/glovebox of anything which is not required for the journey is a good idea too. The amount of people I know with random stuff in the boot they don't need is unreal. Why would you want to pay more to lug things around you don't need?
If you own a coupe with rear seats that never get used then you can save a decent amount by getting rid of them. Pretty pointless in most coupes anyway with the little amount of space available in the back. Worth keeping stored away somewhere though if you plan on selling the car in the future:)
If you still want to retain the comforts without going crazy then other ways to save weight would be swapping out stock parts for lighter equivalents. For example front seats.

No point in going too far on a road car in my opinion.
 
adam1983 said:
If you are a larger person then losing weight yourself is a good way before even touching the car.
Emptying the boot/glovebox of anything which is not required for the journey is a good idea too. The amount of people I know with random stuff in the boot they don't need is unreal. Why would you want to pay more to lug things around you don't need?
If you own a coupe with rear seats that never get used then you can save a decent amount by getting rid of them. Pretty pointless in most coupes anyway with the little amount of space available in the back. Worth keeping stored away somewhere though if you plan on selling the car in the future:)
If you still want to retain the comforts without going crazy then other ways to save weight would be swapping out stock parts for lighter equivalents. For example front seats.

No point in going too far on a road car in my opinion.
Click to expand...

I guess that is the point of the article. If you don't go too far with a road car there is no real point in doing any of it as the little you do won't make any real difference other than more noise and less comfort.

Road car - don't waste your time.
Road/track - Remove easy things - spare tyre, unused seats, loose carpets when on the track and replace afterwards.
Track only - Go whole hog if you want to achieve a real improvement.
 
Last edited:
For use on the road only then I personally would only remove really easy things. Like I said before stuff in the boot that you don't need to leave in. I'm not talking about spare tyres or tools but more along the lines of general day to day items that people tend to just put in and not be bothered moving :)
On a road car it's less to do with lowering 0-60 times but more to do with better mpg. But as mentioned also before that is mainly controlled by the right foot.
Interesting topic though :)
 
We all know that cars go better when they are cleaned outside and in, all the rubbish and clutter gone etc.

This is not psycosomatic.

Nor is it down to carrying less weight (though mass is what we're really discussing, weight is a function of mass and gravity).

The real reason is this ......... You can get the accelerator pedal down further and thus access more of the available performance :D .....
 
HDi fun said:
Nor is it down to carrying less weight (though mass is what we're really discussing, weight is a function of mass and gravity).
Click to expand...

You and I know that, but as we are dealing with mass and a pretty constant gravity, mass and weight are, for all intents and purposes, synonymous as far as this discussion is concenred :)
 
How much performance do we really need on the road anyway. My current car is a 12 year old BMW 528i. Its a hefty piece of metal and the 6spd Steptronic auto does it no favours.

However, it still does the 0-62mph thing in a few tenths under 8.0 seconds. Torquey enough for my purposes. It's not a fast car in my estimation but it's lively enough to get on with the job at hand

And in fairness it does keep pulling as speed builds, handling is more agile than youd think for best part of a ton and three quarters
 
I a quite surprised how many people have agreed with the 'no point' view especially since they can't all be driving stock cars.
Nobody seems to have a problem with tuning a road car so how is weight loss different.. I'm not talking about totally stripping the car but there is no downside to changing say the wheels , seats exhaust etc so why not improve them especially when they need replacing
Also quite a few cars that are used on the road are also used on the track or strip . In these cases weight loss is useful and I would say sensible.
Finally bearing in mind how far people go for a drag or track car it obviously works so why not especially when cost is not the most important factor.
 
I was looking at a news story on a particular BMW model that Waynne posted up the other day. Apparently BMW are going to use considerably more aluminium and carbon in the next range to obtain a much lower weight loss.
It is alleged that this will aid with their quest for achieving lower emissions.
 
SLEEPER said:
I a quite surprised how many people have agreed with the 'no point' view especially since they can't all be driving stock cars.
Nobody seems to have a problem with tuning a road car so how is weight loss different.. I'm not talking about totally stripping the car but there is no downside to changing say the wheels , seats exhaust etc so why not improve them especially when they need replacing
Also quite a few cars that are used on the road are also used on the track or strip . In these cases weight loss is useful and I would say sensible.
Finally bearing in mind how far people go for a drag or track car it obviously works so why not especially when cost is not the most important factor.
Click to expand...

I guess you have to factor in effort against results. It sounds a right ballache to get a small increase. Whereas all i needed to do to get a 26% increase in power was hand some bloke 200 quid and leave him to it for an hour.
 
Yugguy said:
I guess you have to factor in effort against results. It sounds a right ballache to get a small increase. Whereas all i needed to do to get a 26% increase in power was hand some bloke 200 quid and leave him to it for an hour.
Click to expand...

26% increase out of a turbo diesel? Is that all?
 
I like my road cars reasonably quiet & comfortable.. It means i have 2 lots of sound deadening & my full leather stays. I prefer more weight than standard as it aids traction.
If i want more Performance I would build a more Powerfull engine.
If it was a drag or sprint car all those things would be out the window & i would aim as light as possible & tweak my Power curve to give max traction with that weight.
 
It very much as you say ^^^^ - like you I want quiet refinement and comfort in a road car. I cover stacks of miles a year (over 30,000 at the moment).

That's not to say that performance doesn't matter - it does - which is why my cars are properly serviced and I do not skimp on discs, pads, tyres etc. It all makes for a more relaxing drive. And, let's face it - occasionally I do take the long way home to alleviate boredom so it's got to work properly.

There's a small obsessive part of me that drives me to have things arrow straight and perfect - I sit narrowly on the Autism Spectrum (mild Aspergers). Not a bad trait in my opinion

Good post Mister Rod
 
Not having OG's arrogance on this one. One step too far. I have PM'd him already

This is supposed to be a non jugemental forum.

OG, You retract your statement about OCDs please else I am out of here forthwith

Mental health is not the butt of jokes

I am pleased you have never encountered such stuff
 
Last edited:
My reply was meant for T9!!!!! Not you, Paul. If you look, you will notice that I was replying to his post, not yours.

He knows that I was only joking, as you can see from his reply. The amount of time, effort and attention to detail he lavishes on his car................:)

However, I am more than happy to retract my statement if it has caused offence, even if it is a missunderstood offence.
 
Last edited:
You must log in or register to reply here.
Similar threads
Thread starter Title Forum Replies Date
thexav What does GTI stand for General car Chat 2
thexav What does SUV and Crossover SUV mean? General car Chat 1
thexav What does water injection actually do? General car Chat 3
thexav Is global warming a real thing and does it worry you General car Chat 13
obi_waynne What essential ingredients does a fun car need? General car Chat 6
obi_waynne Speed kills, or does it. General car Chat 12

Similar threads


Please watch this on my YouTube channel & Subscribe.


Back
Top