Mercedes Benz clr vs Lotus 15: Ultimate Comparison

Short Introduction about Mercedes Benz clr  vs Lotus 15

The Mercedes Benz CLR and Lotus 15 are one of the most unreliable sports racing cars ever built. They both had stability issues and low levels of reliability on the tracks. The Mercedes Benz CLR was so terrible that one of the models flew into the sky and flipped three times during the 1999 24 hours of Le Mans.

The Lotus 15, despite not causing any serious accidents, did not provide a high level of reliability due to the combination of parts used. The company chose to unite a Grand Prix engine with a Lotus transaxle that it had innovated. The combination led to impressive high speeds for its time but had low unity and seamlessness on the tracks.

When comparing these two European race cars, you will notice that the Mercedes Benz CLR is the clear champion. A large contributor to this is the V8, mid-mounted longitudinally, naturally-aspirated engine capable of outputting 610 horsepower. 610 hp is 470 horsepower more than what the Coventry Climax straight-four Lotus engine can produce.

For this comparison, we are going to focus on the unique features that these two racing cars provide. We will also look into their various contributions to the race car world and how they changed the scene. Since these cars are high-end custom race cars, do not expect to find one easily, and even if you do, expect to dish out millions of dollars to purchase just one.

Specification comparison

 Mercedes Benz CLRLotus 15
Car typeSports racing carSports racing car
Production year19991958-1960
How many units produced428
Estimated cost today$2,000,000N/A
Curb weight2,000 pounds/ 900 kg450-562 kg / 992-1240 pounds
EngineMercedes Benz GT 108 C 90-degree V8, mid-mounted longitudinally, naturally-aspirated engineTwin-camshaft Coventry Climax straight four FPF:1956 FPF 1475cc 4 cyl 3.20 x 2.80″ 1957 FPF 1964cc 4 cyl 3.40 x 3.30″1958 FPF 2207cc 4 cyl 3.50 x 3.50″ 1958 FPF 2467cc 4 cyl 3.70 x 3.50″
ValvetrainChain driven DOHC, two valves per cylinderChain-driven DOHC, two valves per cylinder
Engine capacity5,721 cc /359.4 cu in1965 cc/ 119.91 cu in
Fuel capacity15.9 US gallons / 60.19 liters19 US gallons / 71.9 liters
Bore90 mm / 3.54 inches3.4 inches/ 86.4 mm
Stroke45.8 mm / 1.8 inches3.3 inches/ 83.8 mm
Compression ratio12.8:112.4:1
Maximum Power610 hp / 449 kW  140 hp / 104.4 kW 
Body frameChassis made out of carbon-fiber and aluminum honeycomb monocoque structureAluminum body over a 1.75-inch square and round tubular steel space frame
Front tiresBridgestone 4.5 inches 
Rear tiresBridgestone5.5 inches
Front brakesAll-round ventilated carbon-ceramic discs.Inboard discs
Rear brakesAll-round ventilated carbon-ceramic discs.Inboard discs
SuspensionFront: Pushrod-activated coil springs over Penske dampers with double wishbone suspension, anti-roll bar.Rear:Pushrod-activated coil springs over Penske dampers with double wishbone suspension, anti-roll bar.Front: Coil-over dampers with double-wishbone suspension.Rear:  Coil-over dampers with trailing arms and Chapman Struts. 
TransmissionXtrac six-speed sequential manual transmissionFive-speed sequential manual transmission
Acceleration0-60 mph in 2.7 secondsN/A
Maximum speed217 mph / 349 kph140 mph / 225.3 kph

A Brief Historical Background

Mercedes Benz CLR

To compete in the 1999 24 Hours of Le Mans, car manufacturers were expected to adhere to the new Le Mans Grand Touring Prototype (LMGTP) regulations. The LMGTP regulations made sure that car manufacturers did not have to build road versions of their cars allowing more creative freedom for the chief designers.

Another regulation in the LMGTP was that the minimum acceptable weight was reduced from 950 kilograms to 900 kilograms. The weight reduction allowed the designers to build the Mercedes Benz CLR with a smaller cockpit than its predecessors. The development of these regulations is what led to the construction of the CLR which was intended to be a savior for the German company. 

In 1998, Mercedes had dominated the FIA GT Championship that most of its competitors decided not to race in the 1999 FIA GT Championship. The 1998 records had been set by the Mercedes Benz CLK GTR and CLK LM. These vehicles were fast but failed when it came to reliability, some of them experienced mechanical failure and malfunctions after just three hours of racing. 

The CLK LM and CLK GTR failed to compete well in the FIA GT Championship due to the fierce competition from Porsche. Therefore, Mercedes opted to join the Automobile Club de l’Ouest (ACO), organizers of the 24 Hours of Le Mans’ LMGTP category with the Mercedes Benz CLR.

The CLR borrowed a few elements from the CLK LM such as the carbon fiber and tubular steel frame bodywork. They did not replicate the design entirely, a few modifications such as the inclusion of a nose that was placed lower and flatter than the predecessor.

Only three CLRs were made, all of which were entered into the 1999 Le Man’s race. They were placed in No.4, No.5, and No.6. The race would eventually go down in history as one of the most memorable races of all time. They did not win the race since Toyota and BMW were dominating the track at the time, leaving Mercedes with the fifth, sixth, and eighth positions respectively.

During the second day of racing, Webber who was driving the No.4 CLR got into a serious accident. Webber tried to overtake the leading Audi R8R only to end up airborne as the CLR raised its nose and wheels flipping upwards. The car somersaulted to the back hitting the tarmac road and skidding approximately 980 feet onto the safety barriers.

Webber survived with less serious neck, back, and chest pains. The No. 4 CLR was repaired and put back in the race only to end up having the same accident during the warm-up session. The car rose over 30 feet in the air and hit the tarmac road so hard that the engine cover was shed. Mercedes withdrew the No.4 CLR thinking it’s the only one with a malfunction.

The No.5 CLR, driven by Dumbreck, was the next one to fly into the air. As the car ran its 76thlap, it was suddenly lifted upwards to a whopping height of 50 feet while rotating three times in the air. The third accident marked the retirement of the Mercedes Benz CLR that would never race again.

Lotus 15

Built between 1958 and 1960, the lotus 15 is a front-engine, two-seater race car that came in an aluminum body and tubular steel space frame. It is the successor to the Lotus Mk X and was later succeeded by the Lotus 19.

The Lotus 15 was built in three series. Series 1 was built for the Formula Two and Grand Prix championships. It featured a Lotus five-speed sequential gearbox and a four-cylinder Coventry climax engine capable of 1.5-to-2.5-liter displacement. 

The Series 1 first performed in Sussex Trophy in April 1958. Sadly, it did not even finish the race because of some malfunction in the gearbox. The Series 2 aimed at fixing the gearbox issues experienced in Series 1, additional changes were also done to the Series 1 engine to lower the center of gravity.

Series 3 came out in 1959 with an improved and more reliable transaxle and dry-sump lubrication system. The tubular steel frame was also reinforced to make up for the shortcomings presented in Series 1 and 2.

The fifteen only won the 1960 Australian Tourist Trophy and the 1961 Macau Grand Prix. The vehicles never had enough endurance to outperform other vehicles from Porsche and Mercedes. Its reliability was so horrible that it failed to complete the 24 Hours of Le Mans, not only once, but twice – in 1958 and 1959.

Experience Comparison

As earlier stated, these two vehicles were not reliable at all. They both failed to achieve the needed results with various design flaws and complications. They were both fast vehicles for their time, they failed when it came to stability and endurance.

The Mercedes Benz CLR’s tragic accidents were due to the design of the long rear and front overhang. The design flaw was discovered by ACO, who later modified the LMGTP regulations to reduce the acceptable length of rear and front overhang. Despite its catastrophic failure, the CLR has been praised by some drivers saying that it had great handling and incredible technology that gave it an edge over most race cars.

Lotus 15 had a low level of reliability due to the mixture of a Grand Prix engine and the Lotus transaxle. The components did not interact seamlessly, resulting in low levels of endurance. The vehicle was however capable of incredible top speeds of 140 mph. Sadly, high speeds are not everything since the 1965 cc engine could not provide enough endurance to finish the 24 Hours of Le Mans.

Suspension Design Comparison 

Lotus 15 features a Chapman Strut rear suspension that also came with inboard brakes. The front suspension system featured Coil-over dampers with double-wishbone suspensions. The system is no different from the Pushrod-activated coil springs over Penske dampers with double wishbone suspension, anti-roll bar.

The two suspension systems were capable of providing enough shock absorption and comfortability in the vehicles over hours or facing. There were no reported mechanical failures with these systems, and therefore, no upgrades were ever done to drastically change them.

Aerodynamics Comparison

Lightweight is a great advantage when it comes to aerodynamics, and this is where the Lotus 15 shined. It featured a lightweight multi-tubular space body frame designed for efficient aerodynamics by Frank Costin from De Havilland Aeroplane company. The aerodynamic style design enabled the Lotus to achieve incredible speeds that won it the two trophies.

CLR featured the best aerodynamic style with its low center of gravity and low profile. The only area the Lotus 15 dominates the CLR is the curb weight. The Fifteen is lighter with a curb weight of just 450 kilograms compared to the 900 kilograms on the CLR.

Despite the almost double wight, CLR is still the fastest and best accelerator, capable of, moving from 0-60 mph in just 2.7 seconds.

Engine Comparison

The Mercedes CLR has the best engine among the two. The Mercedes Benz GT 108 C 90-degree V8, mid-mounted longitudinally, the naturally-aspirated engine was capable of producing 610 horsepower. Its engine capacity was 5,721 cc capable of handling a fuel capacity of 15.9 gallons.

The Lotus on the other hand had several engine specifications throughout its lifespan. The base engine was the twin-camshaft Coventry Climax straight-four FPF with the following alterations throughout the years:

  • 1956 FPF 1475cc 4 cyl 3.20 x 2.80″ 
  • 1957 FPF 1964cc 4 cyl 3.40 x 3.30″
  • 1958 FPF 2207cc 4 cyl 3.50 x 3.50″ 
  • 1958 FPF 2467cc 4 cyl 3.70 x 3.50″

With the 30–40-year age gap, you can tell that the Lotus’ engines were not horrible performers but they could have done better. The top speed of 140 mph wasn’t bad but the endurance levels against bigger machines in the Le Man’s race brought it down.

Safety Comparison

The only safety concerns for the CLR and Lotus 15 are the length of overhang and gearbox respectively. The longer front and rear overhang on the Mercedes CLR caused it to lose enough downforce and traction to send it up in the air. The discontinuation of the CLR was a clear indicator of how dangerous and unacceptable the CLR’s safety levels were.

The Lotus transaxle and gearbox featured a five-speed sequential manual transmission that became the vehicle’s Achilles Heel. The gearbox was so bad that in April 1958, Graham Hill, the Lotus 15 driver, was forced to abandon the race due to gearbox malfunctions. The company later fixed the issue with a new and improved BMC B-series four-speed transmission. 

Lotus 15 is the safest of the two since it never experienced any serious accidents, if any, like the Mercedes CLR.

Final Thoughts

All in all, these two models are only similar when it comes to their low levels of reliability and the fact that they both didn’t live up to their expectations. Developed as future championship winners, the Mercedes Benz CLR and Lotus 15 went down in history as flops and a cautionary tale to future race cars.

Despite their race failures and disappointment, these vehicles were still great machines with incredible performance and technology. You find it hard to locate one of these vehicles today, only CLR has been put on sale for $2 million while the Lotus 15s are all sold out. It is important to also note that these vehicles are not road-worthy but will make for a great addition to a collector’s library.

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