Help me settle an argument - LPG in an SL?

[peter_964rs]

A friend of mine has seen my SL and now lusts after one, however as a fertile kinda guy he keeps making babies and so has to also buy people carriers and watch the pennies. He's convinced LPG in an SL is a great idea. I'm deeply, deepy sceptical. I attach the email back and forth argument below for your amusement and welcome any opinions one way or t'other!

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J: Have you priced an LPG conversion? An 500SL with the fuel costs of a medium hatchback would appeal to a miserly old git like me.
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Me: I figure running costs to be low given the expected minuscule depreciation as an offset to higher fuel consumption (which, on longer runs, averages 24mpg). I know that sort of thing turns you on as a sprog-producer and owner of people carriers. So LPG is probably not a good idea because installation+lower resale or installation+LPG removal costs would offset the fuel price advantage……..
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J:I can’t see how LPG would lower resale value? Quite the opposite surely.
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Me: Duh? Big LPG tank? In the boot as the only available spot therefore consuming the boot? Think about it. Also think about who would be likely buyers of an SL and whether they would touch one that had been converted and/or converted back again unless presented at a truly attractive price, ergo more depreciation ergo more offset to counterbalance the lower fuel cost (and lower economy probably exacerbated on a big-engined car) not including expensive (probably) conversion/reconverstion costs.



Let’s kill this if you’re still a fan: go find out how much it’d cost to convert an SL500 (or lesser SL) to LPG, how much fuel you’d expect to spend and make a punt on re-saleability based on a car with almost no boot space left and factor in a (large) depreciation cost.



Then factor in the price of doing nothing and paying more for fuel (of which you will be using less).



I am prepared to be impressed…..
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J: Well the Shogun was about 1600+vat and the 323 £1300+vat. It really depends on the complexity of the engine. The tank can come in a number of forms but one that replaces the spare wheel is most discrete. Even one that sits in the boot will take up say a quarter of the boot. This could be easily be a long narrow tank at the back of the boot that is not seen too well from the outside.



If I was offered two 500 SLs, one that was converted by a government approved agent and one that was not converted then I would choose the LPG one. I wouldn’t expect to pay less for the lpg car. In fact if you have a petrol 4x4 these days it’s almost unsellable unless it has been converted to LPG. I was lucky to get £1400 for my shogun. It cost me £4500 2 years beforehand.



Admittedly the buyer of an SL is different to that of a 4x4. However the ‘green’ pressure from the government is increasing year on year. We are already seeing draconian measures in London against 4x4s. Super high road tax for supercars, etc. I could easily predict the opposite of what you are saying. E.g. a performance car without lpg would be seriously devalued by the cost of owning and using such a car as it gets older.



I’ve no idea what the government has in mind in its efforts to pick on easy pollution targets, e.g. the motorist. But the few schemes that are around tend to favour engines and fuels with low c02 emmisions or from a renewal source such as biodiesel.



On a monetary front it may not make sense for your usage profile however I cover 18-20K miles a year so it would make a big different to mine
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Me: I am going to post this on the Bezworld forum and see what I get!
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Actually I didn't send the last bit, I figured I'd poll for replies and see what I got then present back a "fait accompli". Incidentally, I bought my 1998 SL for £15k with 55k miles on the clock and expect the major depreciation to be done by now hence running costs are effectively low.

[RedLiner]

I don't think a car like the SL500 should be even considered for a LPG conversion. Lets face it, an SL500 driven in the manner that most of us lot do (), is going to use a lot of petrol and quite quickly.
If you can imagine the gas compressed into a liquid it roughly equates to the same amount of petrol e.g. 23 mpg of petrol or LPG.
Using fuel at the rate of an SL 500 you would have to have a huge network of LPG filling stations to guarantee you wouldn't run out of LPG.
Another consideration is the weight. An LPG tank holding the same amount of liquid gas as petrol would probably weigh five or six times what the mild steel petrol tanks does.
I would also imagine that a modern LPG gas system would be very complicated and expensive to fit and maintain.

At this point I can reveal my 'Bona Fides' in respect of LPG gas conversions
When I was a teenager I used to have an old Austin A60 estate car, and one year when there was a fuel crisis, I converted it to run on LPG propane gas.
I drilled a hole in the carburettor venturi and bolted on a hollow brass spigot. Flexible gas tube then ran from the carb into a modified standard gas regulator, and then piped on to the propane gas cylinder which was placed upright between the rear passenger seats.
I also mounted a switch on the dashboard to switch the electric fuel pump on and off.
The procedure was to switch on the fuel pump and start the car on petrol. After a few hundred yards I would switch off the fuel pump and when the car started to splutter I would reach behind and turn on the gas valve and away it used to go.
It would only start on propane if the engine was really hot.
An unexpected benefit was the propane gas cylinder would ice up with a thick frost which was wonderful in August, just like air-con. Also the cylinder would only frost up to the level of the propane inside, so I had a very accurate fuel gauge as well



OH happy days

[Juck]

Originally Posted by RedLiner

OH happy days

lol ,,, Man,, I love people like you. The world would be a boring place without them.

[Bawbag]

Red liner,

I can just imagine my wife sitting in the passenger seat, with a propane bottle
behind her... and me shouting - Yeah - but we are saving money and the enviroment ! ! ( (What Global Warming) )


Peter 964r
I believe converting an SL to LPG would not be very beneficial.. where would you put the weekly shopping of Tesco bags and the wind deflector ! ! ??

Would you convert a Porsche Cayman or 911 to LPG ??

Baw

[ErikFinn]

Redliner - all I can say is just... WOW!!!

I did actually think about converting to LPG as the price is about 1/2 of petrol over here in Finland. The LPG tank would replace the spare tire (but not sure if it's possible with the R129 as the hudraulic pump sits in the middle of it...)

But a bigger problem is that there's only ONE LPG station in the country, and it's 400 miles away...!!! LOL! :-D

A few years back i read an article in the Mercedes Owner where a W140 S320 had been converted to LPG. Also, if I'm not mistaken, quite a few british limousine companies have converted their S-classes to LPG, including M119 engines.

But yes, I'd rather get another car to be used as a daily runner than use the SL daily... I used to have a diesel Golf and was able to get over 600 miles with a tankful, and it was only a 50 liter tank (about 13 US gallons).

[msbarsi]

Hi Peter,
I use my SL 320 as a daily transport and I am quite happy about the mpg returned from the car.
Ok I only do something like 6.000 per year and I have a "Fast and Furious" driving style but I can make a couple of considerations: since your friend has childrens I guess he will be using the SL very little and for fun mainly so I understand he won't have a big per year mileage to cover with the car. If he has to watch every penny like you say he could consider something smaller than the 500 say a 320 (especially in the V6 form since it seems to have a batter fuel consumation) or even a 280.
About the LPG conversion I can tell the experience a friend of mine had with an Audi A8 4.2L V8: the conversion is very costly since what he used 8 injectors (one for each cylinder) using the liquid gas injection or something like that and actually he told me he was very happy with the whole thing and that, running on gas, the car was even faster that running on petrol either.
But we are talking about a 30.000+ miles per year person.
In the SL you could have the spare wheel tyre style gas tank and run on run flat tyres so you would avoid all problems but honestly for the considerations I made before about your friend mileage I don't think it's worth.
As for the resale value, I think that people byuing an R129 will use it as a "fun machine" so an LPG conversion will be on the bottom of priorities list when they hunt for one affecting the resale value since LPG is usually reserved for big mileages.

That's my point of view tho.

Cheers.

[peter_964rs]

Many thanks, good reply which echoes my own feelings. I think he's looking at a daily driver for personal use to and from work and customer sites and would have another people carrier style car for his wife & kids. Therefore a higher mileage for the SL. He wants something prestigious and nice to drive - after all he could always get a diesel Golf and reap the rewards of low running costs, but that's not what he wants.

Despite which, I still feel it's pointless because

1. You have to change the tyres to run-flats
2. It probably won't fit in the spare tyre space due to the location of the hydraulic pump as you say
3. Eight injectors equals much money
4. Who else would want to buy one when he comes to sell it unless it's at a big discount therefore is he actually saving money?
5. It's just wrong....!

[snowbilt]

Now that is thinking outside the box. Really the only reason you listed that is needed to validate this is #5. On a side note I am thinking about transforming my SL into a time machine. The energy source needed to produce this effect will be lightning. If my calculations are correct, it will take 100,000 jiggawatts to produce time travel. I have seen this done with a delorean, but the SL is a much better car.

[RedLiner]

Originally Posted by snowbilt

........ I am thinking about transforming my SL into a time machine. The energy source needed to produce this effect will be lightning. If my calculations are correct, it will take 100,000 jiggawatts to produce time travel. I have seen this done with a delorean, but the SL is a much better car.

Funny you should mention that, would you like one of my 'Wile-E-Coyote' sketches of the plans

[snowbilt]

Liner,

I would like to take a look at it, but I will only accept ACME approved prints. Actually now it seems if I could use mustard as a fuel source it would be more cost effective. You could stop at any gas station or restaurant for fuel. At this point lightning acutally sounds a little wacko.

This post is sponsored by Hendricks Gin tonight,
Chris