Upgraded from R129 SL320 to R129 SL500

[swithin]

I am now the proud owner of a 1999 R129 SL500 which although a bit pricey in this market (£12k) is in my mind perfect. 31k genuine miles since new with interior and exterior in pristine condition.

Although this post will receive some groans, it has also had an lpg tank fitted in the spare wheel well.

The filler is behind the rear number plate so no unsightly cap on the side of the car and currently enjoying 74.9p a litre. It's also great watching others in the petrol station look envious as they realise that they paid more for their "can on wheels" and yet mine is as expensive or less to run everyday.

200 miles on an lpg tank on motorway for £35 and no loss in power.

Now just got to sell my 97 sl320!

Photo's to follow

 

[R2e]

Congratulations! LPG Rules!!

 

[swithin]

As i tell all my mates, its better to drive a car like mine hard rather than like an old woman, trying to eek out every mile out of a litre of fuel.

 

[kth286]

please include photos of number plate flap arrangement - thanks.

 

[74merc]

What size of tank does it have? Were any modifications made to the hood mechanism? Cheers.

 

[EDZ649]

What size of tank does it have? Were any modifications made to the hood mechanism? Cheers.

I doubt it, the hood mechanism doesn't stow in the boot area like the later SL's.

 

[74merc]

Isn't there a member here with an LPG converted 129, who had some modifications made to the hood mechanism of his?

 

[swithin]

The car already had the conversion when i bought it. The workings in the engine compartment are placed to the side of the engine. The 40 litre tank is in the spare wheel well, so i am no longer karting round a heavy lump rather am using the space to move forward.

Other LPG owners are impressed as to where the filler is. The number plate is magnetic and fits neatly over the filling hole. There is no pipe taking up any room in the boot and no modifications needed to the hood mechanism.

Around town I get around 155 miles to a full tank and 199 miles on the motorway. Am will be driving from London to Aberdeen in the Summer and am hoping to not have to fill up on the motorway (647 mile trip).

The best bit however is not being concerned over the MPG needle which does spend a lot of its time buried in the 0-10 range

I will take some shots when i get home and load them up here for all to see.

 

[Will]

Sounds like a great car and very practical too.

Let's face it, for a daily drive car if you can make an R129 SL500 affordable to run like this then why not

Will

 

[MD5]

Sounds great, but I'm curious about the no loss of power, which I thought was a compromise, albeit slight, of lpg? Is this in comparison to your 320 or other 500s?

 

[R2e]

There can be a slight loss of power in the higher rev bands apparently but it shows up more on small engines. I, like most LPG drivers, can discern no difference between petrol and LPG on my ML320 (and to start with I was switching constantly to see if there was any difference!). I think too the multipoint injection systems are less prone to this than older systems.

 

[Sp!ke]

Around town I get around 155 miles

That doesnt sound much more economical than I'm seeing running on the expensive stuff. Thats the equivalent of 30mpg if my calculations are correct.

I appreciate that your car came wth lpg fitted but if one were to go this route, the return on investment is quite some mileage before break even point.

 

[swithin]

I worked it out at around 18mpg average and as i only use it at weekends its not that much of a problem. I travel to work by train during the week. Recovering the investment in the conversion would not have been a problem for me either as the car has only done 34000 miles so will be giving me a lot of pleasure for many years to come. This may even be the last SL I need to buy.

 

[BTB 500]

As above I cannot understand why a car that has averaged 2500 miles a year would have been converted to LPG. Bizarre.

 

[BTB 500]

The 40 litre tank is in the spare wheel well, so i am no longer karting round a heavy lump

I doubt a full LPG tank with all the fittings weighs much less than a spare wheel?!

 

[A210AMG]

40 Litre LPG tank will not hold 40 litres either, how much can you actual get in? have you a little led meter with say 4 lights counting down the tank full / empty?

I guess its a donut tank? similar to what my dad had several years ago in a C200.

My dad currently has a SL500 (the latest shape) and from that he gets 28mpg as it is

Fact it your enjoying v8 power and sound for v6 fuel money so all good.

 

[Sp!ke]

I worked it out at around 18mpg average and as i only use it at weekends its not that much of a problem. I travel to work by train during the week.

This works out to an *equivalent* of around 30MPG based on your 74.9p per litre.

My point is that I'm getting very close to that (28mpg) within the M25 using VPower.

This poor fuel consumption makes me wonder what the fuelling is like and whether it is setup correctly. You wouldn't want to risk washing the bores for a 2mpg saving.

 

[swithin]

Hi Bill, The guy i bought the car off of had a large LPG tank in his garden so obviously paid less than at a petrol station. With regards to weight I would imagine the full tank would weigh about the same as the spare wheel, though whereas the spare wheel is off little use, except on rare occasions, the LPG tank propells the car at a greatly reduced price to unleaded.

 

[swithin]

From absolutely empty I have filled it with around 40 litres of fuel and yes it has the four lights on the dashboard where the switch for moving the headlights up and down was. As to economy it has to go in for a service soon and the LPG guys suggested that following the service where the filters are changed it would improve MPG a little. Hope it does. For me 200 miles for £30 is better than 400 miles for £120

 

[Sp!ke]

I got 450 miles out of £90 on a run last year in mine.

It is normal for me to get 380+ before reserve.