Lexus doesn't mess around when it comes to luxury. In fact, if you could bet on the Japanese brand getting just one thing absolutely bang on, it would be all things plush. Its ability to keep up with the latest in-car technology however is a slightly different matter. Even new Lexus models tend to have a whiff of geriatric-ness about their tech.

But the latest RX 450h+ aims to change that perception, with more modern bells and whistles and an advanced plug-in hybrid system that looks to trump the Volvo, Range Rover and BMW bigwigs. 

What sets the 2.5-litre four-cylinder petrol plug-in hybrid system in the 450h+ apart is its ability to function as a self-charging hybrid when battery power has been depleted, thanks to it having a second on-board battery. With most plug-in hybrid systems, once
battery charge has run out, the car will function like a standard combustion-powered car, utilising engine power alone. For most plug-ins - especially big SUVs with large engines - this can result in fairly in-efficient fuel economy figures.

A full charge of the 18.1kWh battery in the RX 450h+ will get you around 40 miles of all-electric driving. You can choose to hold onto this charge, have the RX function as a regular hybrid, or use it all at once in EV mode. Once you've blasted through this electric range, the second battery will kick in and replenish charge via things like regenerative braking. And it works a treat. This effectively gives you the best of both self-charging and plug-in hybrid worlds.

In plug-in hybrid mode, we managed to achieve an average of around 65mpg. In self-charging "regular hybrid" mode, we achieved closer to 40-45mpg.

Electrified status aside, the RX 450h+ is a pleasure to drive. It offers nothing in the way of sporty fun - it's a hulking 2.2 -tonne SUV at the end of the day - but the comfort on offer is some of the best in the market. The variable suspension irons out bumps and imperfections with ease, yet still offers a bit of firmness overall to avoid feeling wallowy. The steering is nice and progressive too, making navigating urban environments a breeze.

The switch from petrol to electric power is seamless, and while the e-CVT automatic gearbox can be a little hesitant to kick into life when putting your foot down, its slightly laid-back demeanour isn't out of character for the RX.

Even though there's plenty to like about the RX's drive, its interior will probably garner most attention. Although fairly simple in its layout - with a large 14in touchscreen sitting in the centre, surrounded by suede leather inlays - it manages to offer something that feels markedly premium and worthy of Range Rover competitor status.

There are wooden inlays, dampened toggles, soft-close everything and bum-cradling seats that are amongst the comfiest we've ever sat in. 

The touchscreen system is easy to use overall, if not lacking a little originality, but it's slick enough for quick on-road tinkering, and its Apple CarPlay and Android Auto work flawlessly. In general, there's loads of kit on offer - including staples like DAB, Bluetooth, sat-nav and triple-zone climate control. There's also more advanced tech like a 360-degree camera system, a rear view camera which can be viewed in the rear view mirror - even while driving, wireless phone charging and park assist with remote parking option via a smartphone.