So what about the saloon?
The four-door version of the G37 faces an even stiffer test, because the 3 Series saloon has long stood triumphant over the compact executive class.
The engine, gearbox and chassis are taken from the coup so it's frisky enough to drive, and there's plenty of rear headroom, plus a reclining rear seat. However, it starts to stumble when you start to take into account the usual compact exec practicalities. For example, the boot is a bit small and it's difficult for rear-seat passengers to slide their feet under the front seats.
The good news is that Infiniti has made the cars feel well built from top-quality materials, and has stuffed them full of toys, too.
What kit does it have?
Entry-level models have six airbags, electric driver's seat and steering wheel adjustment, a seven-speaker stereo, dual-zone climate control, cruise control, automatic headlights and wipers and parking sensors. The only thing they miss out on is leather upholstery.
Mid-table GT trim adds that leather trim, more electric adjustment for both the driver and passenger seats and memory settings so you don't have to fiddle around endlessly to return the seat to your preferred position after someone else has been driving the car.
Top G37S spec has more-supportive seats, larger wheels (on the Coupe) and a package of upgrades to sharpen the ride and handling. Besides the limited-slip differential and four-wheel steer already mentioned, the range-topping specification also includes stiffer suspension, more powerful brakes and aluminium pedals and footrest.
Options include the seven-speed automatic, adaptive cruise control that matches the speed of surrounding traffic, and satellite-navigation.
So, the G37, in either coupe or saloon form, makes pretty decent executive transport. The problem is that, in the UK where CO2 output is the be-all-and-end-all for company users, it's a range hamstrung by the fact that it won't have a diesel option for a couple of years.
The V6 petrol engine is always going to puff out more CO2 and drink more fuel than an equivalent diesel so you'll be stopping to refill more often than you would than in a BMW. Vehicle excise duty is also higher, you'll pay more in company car tax, despite the Infinitis being slightly cheaper than their BMW rivals, and residual values are unlikely to match those of the German competition.
Nonetheless, with decent products like the G37, and the promise of service levels that will ultimately better the high standards set by Lexus, it surely has a fighting chance.