The old saying of 'two heads are better than one' is particularly relevant when it comes to motors. Some of the most iconic cars have been created when car companies get it on together to create something so epic, that it'll forever be remembered as one of the greats. Here are 5 of the highlights so far.
1. Mercedes and Porsche: Merc 500E
When these two German power-houses got together to brew up a car, they came up with one of the best sleeper 'Q' cars of all time. The 500E's outwardly very similar to the dependable W124 it's based on, but take a closer look, and you notice a few subtle differences. That slightly wider track, those flared arches, the lower stance, it all points towards the fact that this is no ordinary W124. Sure enough, there's a socking great 320bhp 5.0 V8 from the R129 SL stuffed under the bonnet. All this was hand-built by Porsche at its Rossle-Bau factory until the car was discontinued in 1994. Porsche then moved onto its next collaborative effort, the Audi RS2.
2. Audi and Porsche: Audi RS2
The stupendously fast Audi estate is something of petrolhead's idea of perfection. Using Audi's already brisk S2 Avant, the chaps from Stuttgart worked their magic on Audi's 2.2 turbocharged five-cylinder unit, upping the power to 311bhp. The suspension and brakes were beefed up, with the whole shabang finished off with a set of Porsche's 17-inch Cup rims. The results were pretty startling; 60mph flew by in a scant 4.8 seconds, while the top end was electronically limited at 162mph. With the added traction of four-wheel drive, the dash to 30mph was dispatched in a neck-snapping 1.5 seconds, faster than the McLaren F1 hypercar.
3. Lotus Carlton
This isn't the first time the Hethel firm was called upon to beef up an otherwise ordinary car; the Lotus Cortina is evidence of this. But it was the Vauxhall Carlton that Lotus really went to town on. Enlarging the already powerful 3.0-litre straight-six to 3.6 litres and strapping on a pair of Garrett T25 turbochargers, Lotus unleashed a massive 377bhp. Refusing to limit the car's top speed to 155mph - as German car makers were doing - the 176mph Lotus Carlton was the world's fastest production saloon. The thought of a four-door family car that could knock on the door of 180mph caused something of a public outrage at the time, with some even calling to ban the car. It never was banned, of course, and for that, we are thankful.
4. Toyota GT86/Subaru BRZ
The result of Toyota and Subaru's recent joint-venture resulted in a true driver's car that proves you don't need massive power to have fun. The 197bhp 2.0-litre flat-four engine provides enough power for epic drifts, while the pairing's low centre of gravity, make them B-road weapons. Car makers of the modern world take note: we need more motors like this.
5. Aston Martin and AMG
OK, so it's still a little while before we'll see the results of this tie up, but - aside from the fact that we probably have to kiss the glorious Aston V12 farewell - AMG firepower under the bonnet of an Aston Martin can only be a good thing, right?
When collaborations go horribly wrong
Things don't always work out so well when two car makers get together. Alfa Romeo and Nissan's joint-venture of the 80s, for instance, may have sounded great on paper. Alfa styling with Japanese reliability? What could be better? Except the pair did it the wrong way round, marrying up the poor build quality and iffy electronics of the Milanese manufacturer with the boring as hell boxy body of the Nissan Cherry. As far as 'what the hell were they thinking' moments go, this one takes some beating.