Lexus GS review - the alternative executive car choice - Engine and Gearbox

Japanese executive saloons offer a different take on the Germanic norm, with mixed success

Evo rating
Price
from £31,495
  • Handsome; well equipped; GS 300h low on CO2; GS F high on individuality
  • No diesels to truly compete with the class-leaders; hybrids an acquired taste

Both the 300h and 450h follow the same hybrid principle, though obviously in the 450h the electric motor is mated to a larger 3.5-litre V6 engine over the 300h’s 2.5-litre four-cylinder unit. Both are direct-injection petrol engines, the 2.5-litre four producing 178bhp on its own and the V6 288bhp. To that the permanent magnet synchronous electric motors add 141bhp to the 300h's output and 197bhp to the V6, though the gains aren’t as much as you’d imagine when taken as a whole. The maximum system output of the 300h’s two motors is 220bhp, while the 450h produces up to 341bhp.

As with all the current Lexus hybrids those combined outputs drive through an e-CVT automatic transmission and it is undoubtedly the weakest link in the whole mating of electric and internal combustion forces. It maximises efficiency by sitting at the engine’s optimum revs for any particular moment, which does little for refinement when you want to accelerate. It’s fine as long as you don’t ask too much from it, but demand power for an overtake and the engine flares up to high revs and hangs on, in a manner that’s rather unbecoming of a genteel executive class saloon.

Subscribe to evo magazine

Experience the thrill of driving with evo magazine. Subscribe now and get your first 5 issues for £5 or buy the latest issue in all good newsagents!

Once again, it's the naturally-aspirated V8 of the GS F that's most satisfying. With the mantra that there's no replacement for displacement, Lexus has slot the 5-litre V8 from the RC F coupe behind the angular spindle grille. Its power figures don't set any new records, with 471bhp and 391lb ft of torque at its disposal, but with the former developed at a 7100rpm power peak there's a clue to the engine's behaviour - it thrives on revs.

Like the hybrids, it also has the ability to combust using an economy-friendly Atkinson cycle, which holds the intake valve open for a longer duration to reduce the compression ratio. This trades maximum power for greater fuel efficiency. In the F, it's only part-time and reverts to Otto cycle combustion when more thrust is needed; in the hybrids, the electric motor makes up for any power deficit.

Advertisement
Advertisement - Article continues below

The GS F's power is sent through an eight-speed torque converter automatic rather than a CVT, and a torque vectoring differential at the rear wheels. The diff is particularly clever, using electronically-actuated clutches to vary output across the axle according to the car's traction needs.

Advertisement
Advertisement

Most Popular

Visit/alfa-romeo/21322/alfa-romeo-to-launch-new-700bhp-8c-and-600bhp-gtv-coupe
Alfa Romeo

Alfa Romeo culls sports car programme in wake of FCA merger

Italian’s future performance models killed off in favour of more profitable SUVs
11 Nov 2019
Visit/caterham/201924/caterham-620r-v-ariel-atom-35-v-elemental-rp1
Caterham

Caterham 620R v Ariel Atom 3.5 v Elemental Rp1

Flight Club - lightweight track day toys with heavyweight powertrains, Steve Sutcliffe compares them on track at Anglesey circuit in Wales
5 Nov 2019
Visit/maserati/granturismo/201792/maserati-granturismo-zeda-run-out-model-revealed
Maserati GranTurismo

Maserati GranTurismo Zéda run-out model revealed

It’s out with the old, in with the new as the final GranTurismo paves the way for Maserati’s ambitious electrified future
12 Nov 2019
Visit/hyundai/i30-n-hatchback/201775/hyundai-i30-n-versus-hyundai-i30-tcr
Hyundai i30 N hatchback

Hyundai i30 N versus Hyundai i30 TCR

Can Dickie Meaden beat Steve Sutcliffe in a straight(ish) race? We sent them to the Circuit Nuvolari with a pair of Hyundai i30 Ns to find out.
20 Sep 2019