The Opel Insignia, launched in 2009, was a breath of fresh air. Its "blade" styling language was unique and dynamic. It made older Opel models look staid and caught the eye of buyers.

But while the Peugeot 508 was available with a more tax-friendly turbo 1.6-litre, the Insignia's sole powertrain in Singapore was a turbocharged 2-litre engine.

The updated Insignia, which arrived earlier this year, is now offered with only a turbocharged 1.6-litre four-cylinder. The changes made to the car's exterior are subtle - the front grille is now larger, while the chrome strip running across the boot lid is wider.

The styling tweaks to the 508, on the other hand, make it look more assertive compared to the older model, which was introduced four years ago. The front end features new LED headlights (which replace the HID units on the pre-facelift model) and a redesigned grille.

Even more significant than the exterior tweaks are the upgrades to both cars' interiors.

The cabin of the pre-facelift 508 has a dated infotainment system with unattractive orange graphics and no satellite navigation function. The facelifted 508 is equipped with a much nicer infotainment unit, complete with a colourful 7-inch touchscreen and satellite navigation. Like its predecessor, the 508 also has a head-up display to make drivers feel like fighter pilots.

The Insignia, too, sports a snazzy new infotainment system. But it also has a revised instrument panel with a nifty 4.2-inch secondary display called the Driver Information Centre.

Making the Insignia feel even more upmarket are its new digitised air-con controls with dual climate zones. The previous model sold here has only analogue controls and a single climate zone.

The 508 trumps the Insignia in terms of occupant space, though. Thanks to the 508's 80mm-longer wheelbase and flatter rear floorboard, backseat passengers in the Peugeot have more room to stretch out. The Opel, on the other hand, not only has less legroom, but lower headroom too because of the sloped roofline.

The Insignia's seats, however, are more supportive than the 508's, making it the more comfortable option for long drives.

The 508's cabin storage is more generous than the Insignia's. Adding to the 508's usefulness is its boot capacity of 545 litres, which is 45 litres more than the Insignia's.

Both cars have turbocharged 1.6-litre engines with nearly similar outputs (163bhp for the 508 and 170bhp for the Insignia), but it is the 508 that is more athletic. Key to this French saloon's performance is its lighter kerb weight - 1,410kg versus the Insignia's 1,580kg.

The 508 thus has a higher power- to-weight ratio, which contributes to its better efficiency, with a claimed 5.8 litres per 100km versus 6.6 litres per 100km for the Insignia.

Between the two cars, the 508 is not only quicker from zero to 100kmh, but more agile when cornering as well.

While the Insignia is not as dynamic as the 508, it makes up for this by being more refined on the move. The Opel's six-speed automatic is smoother than the Peugeot's and its ride quality is more pliant as well.

The Insignia's cabin seems more solid too - not only is it better insulated, its doors are also heavier and require more effort to open and close.

All told, the 508 suits the keener driver, while the Insignia caters to the motorist who prioritises motoring refinement.

•The writer is with Torque, a motoring monthly published by SPH Magazines.