We chart the progress of our Mazda CX-5 2.2D Sport Nav on its long-term test
Cars with two engines
The 6.0-litre V12 in the Aston Martin Vanquish is often unfairly described as two Ford Duratec V6s bolted together, just as the Volkswagen Group's mighty W12 is likened to a pair of narrow-angle VR6 blocks coupled to a common crankshaft.
Cynics have also questioned the environmental credentials of petrol/electric hybrid techology, on the grounds that a car with two motors is unlikely to be greener than a car with only one.
In the motoring world's mainstream, such models are about as close as you get to two engines in one car but true twin-engined machines do exist. They're far, far rarer than any Toyota Prius and have rarely been seen as anything less than slightly mad.
Mostly they have been restricted to one-offs or home-built specials, although just occasionally a limited series has been built in the belief that two engines really are better than one.
The jury's still out as to whether they are or not but the results can certainly be intriguing (and the technological challenges considerable). Looking at this selection of mechanical oddballs, you can't help wondering wether we've seen the last of their kind.
Conceived by maverick Formula Three racer Paul Emery, and improved upon by none other than John Cooper, the Twini brought a second engine to the usual Mini mix together with four-wheel drive and no fewer than 178bhp. Unfortunately Cooper crashed his, waking up in hospital after landing on his roof.
It could be a bit of a handful on the track too. OK if both engines were working, but as one test driver put it, "if one played up the handling changed dramatically." One entered Italy's gruelling Targa Florio, but somehow contrived to finish two places behind a standard Cooper.
See photos of the Twini Cooper on Bing
Citroën 2CV Sahara
The first motor vehicle to successfully traverse the world's largest desert was a 1922 Citroën, an impressive feat the company chose to commemorate when it came to naming this extraordinary 2CV-based off-roader. Unlike the Twini this one went into production, and was available on special order from 1960 to 1971.
It looked pretty standard, but like the Twini had an extra engine mounted to the rear for additional traction. Fewer than 700 Saharas were built in just over a decade, most customers coming from French oil companies, the armed forces and the police.
See photos of the Citroën 2CV Sahara on Bing
Alfa Romeo Bimotore
In the mid-1930s, keen to steal back the competitive advantage from the Nazi-funded Mercedes and Auto Union teams, Enzo Ferrari, a young but wily team manager at Alfa Romeo, conceived a plan to build a new single-seater with two 3.2-litre engines mounted longitudinally and producing in excess of 500bhp.
The mechanical layout was unusual to say the least, the two engines connected by separate driveshafts to a single gearbox and with each of them driving a single rear wheel. Unfortunately, additional complexity meant any gains in performance were lost in the pits, although one managed an impressive 226mph racing from Florence to Livorno.
See photos of the Alfa Romeo Bimotore on Bing
VW Twin Jet
Someone somewhere has built a twin-engined Beetle where the second one really is a jet, but here the reference is to 'Jetta' - Volkswagen's Golf-based saloon. The Twin-Jet was a one-off design built by Volkswagen Motorsport perhaps in response to the wild success their in-house rivals were having with the original Audi Quattro.
With a matched pair of fairly standard 1.6-litre GTI engines, the banana-yellow mini-monster mustered a fairly respectable 220bhp and weighed in at just 1,050kg. With separate electrics for each engine, the car could also be switched from front- to rear- to all-wheel drive.
See photos of the Volkswagen Twin Jet on Bing
Best remembered for its co-starring role in the enigmatic TV series The Prisoner, for a short while England's own homegrown buggy looked like it might land a job with the boys in khaki. But unfortunately the army turned it down because with only two-wheel drive, tiny tyres and no ground clearance it was lousy off-road.
Somewhat missing the point the makers argued that it was light enough to be carried over rough terrain by four squaddies. When that did not work they u-turned and built the 4WD Twini Moke using two engines, one per axle, but it was too late and the idea struggled to survive.
See photos of the Twini Moke on Bing
The name says it all: VW's smallest car with what were at the time two of its more powerful engines. This was the brainchild of Croatian enthusiast Petar Biocic, who found the time and space needed to cram in a brace of VR6 engines to give it 5.6 litres and an estimated 500bhp.
Inevitably the standard car was hardly up to the job, so scooter dealer Biocic went on to fit Porsche Cayenne six-pot calipers and discs from a Golf Mk5 R32 discs up front, with the Audi RS2 bringing up the rear. Equally inevitably the car has since become an internet sensation.
See photos of the Volkswagen Lupo on Bing
Suzuki Cultus Pikes Peak
A Suzuki Swift, but not as we know it, the extraordinary Cultus Pikes Peak first came to the attention of many enthusiasts via the magic of PlayStation and a role in Gran Turismo 2. The car is real enough, however, and with its wild wings and stubby body beat off all-comers to win 1987's tough All Star Dirt Trial.
On that occasion it was driven by Nobuhiro Tajima, 'Monster' to his friends. Soon to become the first Japanese driver to win the American classic in its near-100-year history, he guided Suzuki's rallying efforts for much of the 1980s and 90s.
See photos of the Suzuki Cultus Pikes Peak on Bing
Cadillac TwinStar Eldorado
After an Initial, private attempt to build a mid-engined Eldorado, Warren Mosler eventually decided to follow the Mini model with separate engines driving the front and rear axles. The one up front is the standard 275 bhp Northstar, with (for a little rear bias) a 300 bhp V8 out the back.
Apparently, because the rear engine has a higher rev limit and uses lower gear ratios, the engines shift up and down at different times as the car accelerates and breaks. According to one road tester this feels normal enough after a while - or at least no weirder than having two engines.
See photos of the Cadillac TwinStar Eldorado on Bing
Definitely not to be confused with the similarly named 207 pick-up, the Hoggar was a 2004 concept with matching diesel engines powering the front and rear axles. With 360bhp and a maximum torque of 800Nm (590lb ft) it was designed primarily to go off-road.
Needless to say nothing quite like it ever made it into production, but its construction was imaginative if a little outlandish. Mostly comprising a one-piece carbon-honeycomb body, it featured twin stainless roll-over bars which cleverly funnelled cooling air into the front and rear engines.
See photos of the Peugeot Hoggar on Bing
Maserati Tipo V4
The official name is something of a misnomer, referring to the cylinder formation and capacity in litres rather than the actual number. More sensibly the car, masterminded by Alfieri Maserati himself, was known as the Sedici Cilindri ('16-cylinder') being built around a pair of 2.0-litre Tipo 26B engines sharing a common crankcase.
With 55 ball races, nearly three dozen gears (plus another eight in the oil pumps) 2 crankshafts, 16 sets of con-rods and pistons, 32 valves, 64 valve springs, four camshafts, two superchargers, four oil pumps and two water pumps - there was an awful lot that could go wrong, and mostly that is what happened.
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