Lighten Car Weight

[Greg8325]

What are the best ways to lighten your car's weight?

[Snax]

The cheapest is to eat less.

Many people start with removing stuff like the spare tire and jack. That's usually worth 50 lbs or so to start with and is easy to replace - but can really suck later on.

The back seats of some cars are also exceptionally heavy and relatively easy to remove. Similarly the rear seat belts can carry significant weight. I know that the ones from a Geo Storm are about 3 lbs each for instance.

I went through this whole song and dance with a race car before and managed to remove close to 200 lbs of stuff overall without going to composite panels and such. That worked out to a slightly better than 7.5% reduction in weight and a car that was really pretty miserable to drive around on a daily basis.

Regardless, I think the whole weight reduction idea for better fuel economy is generally a bad idea. So much more can be saved by simply planning trips better and driving efficiently, and a 5% reduction in weight does not net a 5% reduction in consumption. (Plan on less than 1% improvement.) It's just not worth it IMO.

[onefastcar]

rotating mass, light wheels, light crank pulley, light flywheel.

[RoadWarrior]

I'm not a fan of leaving spare and jack behind, I even have 30lbs or so of spare fluids and tools I won't take out. (Hey, you never need them until you don't have them) Then in winter I have a bag of salt, full size shovel etc. All that to me is "essential" weight. If I was just grinding round the city all day, I might lose some of that, but I don't think it dings highway mileage noticably.

[Jay2TheRescue]

Originally Posted by RoadWarrior

I'm not a fan of leaving spare and jack behind, I even have 30lbs or so of spare fluids and tools I won't take out. (Hey, you never need them until you don't have them) Then in winter I have a bag of salt, full size shovel etc. All that to me is "essential" weight. If I was just grinding round the city all day, I might lose some of that, but I don't think it dings highway mileage noticably.

Maybe switch a full size spare for a donut spare, but never leave yourself without a spare...

-Jay

[theholycow]

I have to agree with Snax. Unless your driving is only stop-and-go dense city driving, it's unlikely that you'll see enough savings from weight reduction to be worthwhile.

The reason why lighter cars can get better FE is because they can have smaller/less powerful engines and/or taller gears while still offering enough acceleration for people to buy the car. Removing weight from an existing car just doesn't seem to make much difference.

[Snax]

Putting this into hard numbers another way. If you reduce the weight of your car by 10% and spend as much as 25% of your time accelerating (the only time smaller weight savings makes a significant impact), the MOST you could save would be 2.5%. More likely however it will be a stretch to remove that much weight without serious compromises, and 25% of your time accelerating would be pretty excessive.

I know, you didn't ask for a lecture in why not to do it, but grant us the courtesy of understanding that you are a noob here and we are obligated to point out the relative futility of weight reduction. If you still want to do it, I'm sure we can offer more suggestions.

[Sludgy]

Another problem with lightening a car: Since all cars rest on springs, simply reducing weight will make a car ride higher and be less aerodynamic.

Wheels, tires and brake drums and rotors ("unsprung weight") are about the only things that can be lightened without hurting a car's aerodynamics at the same time.

If you really want to reduce weight, for example with carbon fiber hoods and trunk lids, etc., and removing seats, the springs should be replaced at the same time to keep the same height or lower.

[SolidLiquidSnake]

.....But if you wanted to be a FREAK about it, you COULD take out that spare and jack and just carry your cell phone with you at all times so you can call somebody else to be the b!tch. ha!

[opelgt73]

Originally Posted by SolidLiquidSnake

.....But if you wanted to be a FREAK about it, you COULD take out that spare and jack and just carry your cell phone with you at all times so you can call somebody else to be the b!tch. ha!

I replaced my spare with a large can of fix-a-flat and a AAA card.

The thing I keep forgetting to buy is a puncture repair kit.

[Greg8325]

Sorry I'm such a noob. I'm just starting to learn about this stuff. I thought that weight reduction was one of the easiest ways to get more mpg.

[RoadWarrior]

Sort of, it is for the untrained driver that doesn't anticipate the road ahead, i.e, those that are either on the gas or brakes all the time, since they spend a LOT of gas accelerating all that mass. The mass is an energy storage device though, once you learn momentum management and to anticipate stops and traffic patterns, much of the benefit goes away. On a steady highway drive it only has any bearing on FE in the 10 seconds you get to highway speed, in the city it's that 10 seconds slow acceleration at every stop light, so in city driving it counts more.

[theholycow]

Nope.

Probably the easiest way to get more MPG is to inflate your tires beyond your car manufacturer's recommendation but not beyond the tire's rated maximum (check the link in my sig about tire pressure). Remove any unnecessary external accessories such as antennas and racks.

It's the easiest, but it's not very effective. The most effective way is to alter your driving habits. You can read all about that in the various discussions here, or review an introduction article such as the one linked in my sig.

[KARR]

For a hypermiler, weight reduction is always useful, if keeping the same way of driving. It will pay off I think.