1991 Mercedes-Benz 420SEL (W126)

When this car was built Mercedes engineers dictated how a car was built, and the result is a vehicle that will easily cover a quarter of a million miles without needing any major work. 

The W126’s replacement was the W140 and was again the work of Mercedes chief designer, Italian Bruno Sacco. The later car is another fine machine, but Sacco was unhappy with the roofline, which he considered too high.

This car was off the road from October 2014 to December 2022, during which time both front wings were replaced with original M-B parts. In December 2022 it was bought by the present owner and carefully recommissioned.

The owner is a serial Mercedes enthusiast who has owned many over the years, and always regretted selling a 560 SE that he used to drive from Greece to the UK. When he found this car he jumped at the chance.

The fit and finish on the two replacement front wings looks very good. The bodywork appears very sound but the paintwork has various scuffs and scrapes. Both sides have significant scratches along them.

The plastic mouldings on the lower areas of the car are also carrying a reasonable amount of marks. Overall, the car presents well but it also looks as though a machine polish and some careful touch up work would take it to the next level.

The rear bumper has some rust damage and ideally needs replacing, but the 16 inch Mercedes alloy wheels are in reasonable shape, with no kerbing marks, although their finish looks a bit flat.

The military spec build quality continues inside this top of the range saloon, and at this kind of mileage you might expect a lesser car to look rather tired. But the cream leather is still in good condition with no tears or rips, and the dash is in similarly good order.

At some point the car has had a tracker fitted, the remnants of which is a working key in the glove compartment (which switches on the hazard lights). 

The roof lining is in good condition but the trim near the rear window needs to be refitted properly as it has dropped. 

The owner tells us that all the electric windows work, along with the sunroof, driver's electric seat and the nearside mirror. The original Blaupunkt radio is present but has not been tested. The heater works but the A/C has not been tested. The bulb to the left of the instrument console needs replacing and a new one comes with the car. 

The walnut woodwork and dashboard are in excellent condition with no splits or cracks. There are two keys present, and one single key works in the ignition, glovebox, central console and the boot. All tools are present in the boot.  

The rear parcel shelf is original and has no sign of rust or deterioration, a frequent problem with these cars due to a rare design flaw.

Earlier versions of the W126 with a 3.8-litre version of the Mercedes M116 V8 engine had a single row timing chain that can stretch and cause problems, but later versions such as this 4.2-litre M117 example have a duplex chain, which causes no such issues. 

168,000 miles on a bread and butter 1987 car might be considered a high mileage, but this W126 is capable of 300,000 without major problems. These engines are all alloy and have no steel cylinder liners, instead relying on a special honing technique to produce a high silicon content bore, which is incredibly hard wearing.

And despite later cars from BMW and Jaguar with Nikasil bores suffering from problems as a result of high sulphur content fuel, the Mercedes M117 V8 never had these problems. 

The single overhead cam per bank V8 is in reasonable cosmetic condition on this car, with surface blemishes on some of the plated components and alloy parts. The engine idles and runs smoothly. The owner says that the engine starts first time, every time and that it's a pleasure to drive with swift and smooth acceleration and excellent road-holding for such a big car. 

The owner tells us there is a slight blow from the exhaust, which needs attending to.

The owner tells us that this SEL was first owned by a company CEO, who cared for it meticulously. He says:

‘Every single receipt and event is recorded in detail on the service logbook and in receipts in a thick folder that came with the car when I bought it. 

‘There were a couple of other owners until the one prior to me, who had had it for about eight years from late 2014 to late 2022, when I bought it. During that time, he replaced the front wings and I think also the bumpers. Sadly he died and the car, which he had dubbed 'The Count', was sold by his daughter to me in September 2022. 

‘I had sent a mechanic friend to test drive 'The Count' for me as I was living abroad at the time. It appeared to drive well at the time and on that basis I bought it, as I had been looking for a W126 for quite some time and this seemed to be The One. I had the tyres changed before I picked it up in December 2022. However, when I took it away it drove terribly. There was clearly an issue with the fuel system, probably caused by being suddenly brought 'back to life' after such a long time idle.

‘I had my mechanic friend look at it and it took a few months to sort out as we had to wait for new or used parts from UK and Germany-based Mercedes-Benz new and used or reconditioned car parts suppliers. There was also some slight water ingress to the front nearside interior floor, which was finally tracked down to rubber seals in the front bulkhead which had become misshapen during a carphone installation, and a perished nearside front door rubber, which was replaced with one from the SL Shop. The car is now dry and watertight.

‘Items replaced during recommissioning included the fuel distribution head, fuel pump, most of the fuel lines and rubber seals. Eventually the fuel system was sorted out and the car is now running perfectly. As well as a complete end-to-end overhaul of the fuel system, the HT leads, sparks, all belts, front shock absorbers, and viscous fan hub were replaced along with all 4 tyres, and windscreen wipers.

‘The brake pads and handbrake shoes were also replaced, and the car was fully serviced. It now has an MOT until 17 April 2025.

‘I am working abroad so have not been able to drive it much, but I did have the pleasure of using it for a week in April 2024, when I drove it in London and around the Cotswolds, where it felt right at home. Unfortunately, the car is not ULEZ compliant or old enough to be exempt and, as I live in the ULEZ zone and work abroad, it is not possible for me to keep it any longer, and sadly it has to go.

‘Its overall condition is excellent for a 33 year old car.  The recorded mileage is 114,172 but the speedometer was changed at 54,000 miles on 16 June 1994, so the actual mileage is 114,172 + 54,000 = 168,172 miles. 

'Unusually for most UK-based W126s, there is no rust except for minor rust under both rear doors and at the top of the offside rear bumper. The car has a complete Mercedes Benz and, latterly, specialist service history and logbook, and a meticulously detailed folder of work and services undertaken during its lifetime.' 

Maybe we’re biased, but we think this is peak Mercedes. And he may be biased too, but the car’s designer, Bruno Sacco, obviously agrees, as he still uses a W126 as his daily driver. 

We are happy to offer this vehicle for auction with an estimate in the range of £5,000 - £7,000.

Viewing is strongly encouraged, and this lot is located at Bonhams|Cars Online HQ. Viewings are strictly by appointment.  To make a booking, please use the Contact Seller button at the top of the listing. Feel free to ask any questions or make observations in the comments section below, and read our ‘Frequently Asked Questions’.