My friend, meanwhile, was in a right old pickle: wait for the newer, prettier 4-series and put up with the four-cylinder diesel engine – or get a new six-pot 3-series saloon in half the time, with more performance and more standard equipment, for less money a month? It was grunt versus grace, and desirability versus the discount.
His monthly saving would probably be more than offset against greater insurance and fuel costs for the 330d – but which car would give him the bigger buzz?
Being something of a brick, I volunteered to find out, imagining that this would be a straightforward choice, on behalf of a fairly low-mileage private buyer, of either 255bhp or 181bhp. Easy peasy. But with the two cars side by side in a Wiltshire car park, the complexity of the decision fully reveals itself.
Read the full BMW 3-series review
This new 4-series is a handsome thing. It makes the 3-series look unexpectedly dumpy and awkward – all straight-sided from the rear end and ill-proportioned in profile.
The frameless doors, elegant roofline and eye-catching details of the 4-series all contribute to a much more appealing overall impression than the 3-series gives. Which is saying something considering that, to these eyes, a 3-series is still about the best-looking ‘normal’ compact exec you can buy.
On the inside, the cars are much less easily separated. To be frank, the 4-series’ cabin designers ought to have done more. The architecture, material richness and finish of both fascias are identical. You sit slightly lower in the 4-series and feel a touch more intimately cocooned by the nearer driver’s window and roofline, so the 4-series feels a bit more special, but not much.
In the back, the relative shortage of passenger space in the 420d is big enough to notice. And although the 4-series’ boot is easier to access, it’s slightly narrower and shorter than that of the 3-series.
It’s not often that a road tester gets handed two cars as precisely matched as these to compare. Then again, all-BMW twin tests aren’t normally as interesting as those involving other brands as well. This one’s certainly not short of intrigue or subtlety, though.
BMW supplied our pair with matching xDrive four-wheel-drive sport automatic transmissions and similar adaptively damped M Sport suspension set-ups, in similar M Sport trims – even with identical alloy wheel sizes and tyres. And yet they are more different to drive than the gap between their respective engines and performance levels would suggest. And that, in itself, is a pretty big gap.
There are, of course, fundamental differences between a 3-series and a 4-series that account for some of the disparity between their driving experiences. Lower and wider of both body and axle tracks, the 4-series has its own chassis tuning, intended to convince you that it’s more spry and precise than its cheaper sibling. It works.
The Gran Coupé feels a shade more taut in its body control and crisp in its directional responses than the saloon. Although outright grip levels are as evenly matched as you’d expect and both cars have excellent cornering balance, the 4-series is just a little bit more eager and direct as you turn the steering wheel.
Read the full BMW 4-series Gran Coupé review