In various guises, the McLaren M16 saw frontline service as a works entry in IndyCar, racing for five seasons, and in effect mirroring the long career of the M23, the F1 car that was a born a couple of years later. The M16 would log three Indy 500 victories over its remarkable lifetime, making it one of the most successful designs in the history of the race.

McLaren first ran a works team at Indianapolis in 1970 with the curvy M15, which also appeared in the other big 500-mile events at Ontario and Pocono. The team was already well known in the USA through its Can-Am involvement, and while the cars were admired for their design and construction, results were modest.

Starting fresh

Designer Gordon Coppuck decided to start afresh for 1971, and there was no hiding the fact that the all-new M16 (or M16A as later versions caused it to be known) borrowed its wedge shape from the Lotus 72, which had proven so successful in Grand Prix racing in 1970, taking Jochen Rindt to a posthumous World Championship title. Coppuck felt that the sleek shape would be ideal for Indycar racing, and he was to be proved right.

The car was unveiled at the Colnbrook factory in January 1971, some four months before action got underway at Indianapolis. As was standard in those days, it used a 2.6-litre Offenhauser engine, mounted in a supporting frame. The engine was mated to a Hewland gearbox with three speeds instead of the two usually favoured at Indy, the idea being to provide better acceleration out of pit stops.

The sleek shape was created by moving the radiators from the nose to the side, where they were shrouded by fibreglass inlets. Suspension was moved inboard, which helped with aerodynamic efficiency. The front of the car produced a lot of downforce, which was balanced by a rear wing that was neatly incorporated into the engine cover, and cleverly skirted the rules of the time. The car was in effect to kick-start an era of huge wings in Indycars, which led to a massive increase in lap speeds.

Works drivers Denny Hulme and Peter Revson gave the car its first testing miles at Ontario Motor Speedway, before Roger Penske took over and ran with Mark Donohue at Phoenix and Indianapolis. Penske had abandoned plans to run a Lola and had instead become McLaren’s first Indycar customer entrant.

When practice for the 500 started in May, Donohue and Revson set the pace, and left rivals scratching their heads. Indeed Revson ultimately took pole at a record speed, with Donohue earning second place and Hulme – never a fan of ovals – in fourth. With three cars at the front, a debut win for the M16A seemed assured.

In the end, the race proved somewhat disappointing, with Revson managing only a low-key second behind the Colt of Al Unser, Donohue stopping with gearbox problems, and Hulme spinning early on before having engine trouble. Nevertheless, McLaren had made its mark.

Donohue’s parked machine was badly damaged when struck by a crashing car later on, and a new chassis had to be built and shipped to the USA. He duly won at Pocono and Michigan and led at Ontario, only to retire from the latter when he ran out of fuel after a signalling mix-up. The M16A was undoubtedly the class of the field, and both Penske and McLaren now had their eyes fixed firmly on unfinished business at Indy in 1972.

Unfinished business 

McLaren decided to upgrade the basic design for the new season. The M16B featured a range of modifications, including new wings, suspension geometry, and radiators. The nose was shorter, which meant that the rear wing could hang further back and keep the car within the maximum overall length.

Roger Penske bought two of the new cars, for Donohue and Gary Bettenhausen. The team’s year started well when the latter won the second race of the season at Trenton in an older M16A.

However, the real prize was Indy. By now, everyone had big wings, and the McLarens were beaten to pole. But Donohue and Revson were again on the front row, in second and third.

Running a conservative strategy that was easy on the engine, Donohue survived what turned into a race of attrition. He led the final 13 laps to give both McLaren and the Penske team their first Indy 500 victories, earning a $218,000 first prize. There was disappointment for the works outfit when Revson and his team mate Gordon Johncock both retired, while Bettenhausen also failed to finish in the other Penske entry.

It was to be Penske’s only Indycar win that year. Not long afterwards, Donohue was injured testing the team’s CanAm Porsche 917, while Bettenhausen was later hurt in a sprint car crash.

The works team only contested the big 500-mile races, and was also out of luck, although Johncock led at Pocono. However in another race of high attrition at Ontario (where Revson started second) the relatively unheralded Roger McCluskey emerged to win for the American Marine team with his ex-works M16A, while back-up driver Mike Hiss was second for Penske.

Donohue returned for the last couple of races with the trusty M16A, finishing second at Trenton and taking pole at Phoenix before retiring.

Enter, Johnny Rutherford

McLaren built six revised M16Cs for 1973, for works and Penske use. By now rule makers USAC had basically said that anything goes as far as wings were concerned. The M16C looked a little more like an F1 machine than the previous car, with a full length engine cover, a new, more rounded cockpit surround, and new radiator ducts. The works team signed Texan Johnny Rutherford alongside Revson, establishing a relationship that would prove to be hugely successful.

Rutherford had a disappointing Indy 500 in 1973, but he won events at Ontario and Michigan with the M16C, and placed third in the championship. Meanwhile Gary Bettenhausen won the Texas 200 with a Penske-run M16C.

Earlier versions of the car would continue to race in private hands for several years. Indeed, in 1973, McCluskey finished third in a dramatic Indy 500 in his M16A, later winning at Michigan and taking three other second places. Against expectations he ended up as USAC series champion with a design that was essentially now two years old.

The 1973 season was a dramatic one for Indycar racing, with speeds rising and a series of spectacular accidents in the month of May rocking the sport. USAC opted to slow the cars for 1974, mandating narrower wings and restricting their overhang. Fuel tanks were also made less vulnerable, and there was more of an emphasis on economy.

Blurring the lines between the M16 and the M23

McLaren updated its existing design to the new rules, and called it the M16C/D. Now it really began to look like the M23, with a similar, shorter nose and a chunky rear wing mounted on a centre pylon rather than the earlier strut arrangement. Indeed with overall length now restricted, the short nose allowed the rear wing to be a little further back than it would otherwise have been.

Also new for 1974 was the absence of the Gulf sponsorship that had proved so successful going back to the Can-Am era, but the works cars initially continued in the familiar Papaya Orange livery.

That winter, Peter Revson left the team to join Shadow for F1 – and Penske for Indycars – although, tragically, he was killed at Kyalami in March.

It was to be a great year for Rutherford, who was now clear number one at McLaren. He won an Ontario heat early in the year and then triumphed at Indianapolis and Milwaukee on consecutive weekends. Another victory at Pocono helped him to second in the USAC championship, although he lost the title to Bobby Unser. Meanwhile Briton David Hobbs finished fifth at Indy in the second works entry, which ran in Carling Black Label colours.

If it ain't broke, don't fix it

The M16 was clearly still competitive, and thus as with the M23, McLaren saw no reason for a radical overhaul. So for 1975 the team produced yet another variation on the theme, dubbed the M16E. This time much of the work was done by Coppuck’s then-assistant, John Barnard. The car had a longer wheelbase and new suspension. Penske opted to stick with its proven C/Ds, which the team itself had updated, so only the works outfit had the new cars.

Rutherford enjoyed another good run at Indy, finishing second in a race cut short by rain. His only race victory came at Phoenix, but he again finished second in the championship, this time to AJ Foyt.

For 1976, McLaren continued with the final E version of a type that had already amassed an extraordinary history, with the newer works cars by now joined on the grid by many earlier models which had moved onto private hands, with varying degrees of success.

Rutherford duly won Indy for a second time, as rain cut the race distance to just 255 miles. He added successes at Trenton and Texas as – for the third time in a row – he was runner-up in the championship, losing out to Gordon Johncock. Mario Andretti took time out from his Lotus commitments to drive Penske’s M16C/D at Indy, where he set the fastest qualifying time, albeit on the second weekend.

Entering a new era

The car was clearly still competitive, but just as the M23 was ready to be replaced by the M26, so the M16 series had come to the end of its competitive life. It was supeceded by the much more modern M24 for 1977, at least as far as the works team was concerned. The change also coincided with a move from the venerable 4-cylinder Offenhauser engine to the new Cosworth DFX.

However M16s of various vintages would continue in service in private hands for several years, all the way through the CART/USAC split at the turn of the decade. Indeed, as late as 1981 – a decade after the type’s debut and long after the works team had given up on America – the car still figured on CART grids. It really was an extraordinary car, and an important piece of our US history.