You might want to check the tech. spec and take a realistic view before committing. Or a longer test drive, a good dealer should let you have it for a day, and do a brim-brim mpg measurement over a couple of 100 miles of your usual sort of driving.
From Hyundai EU website:
TUCSON Hybrid
The TUCSON Hybrid is equipped with both a petrol engine and an electric motor: a so-called full-parallel hybrid drive system. They work together with the support of a 1.49 kWh lithium-ion polymer battery to deliver maximum efficiency and inspiring performance. The hybrid powertrain switches seamlessly between the petrol engine and the electric motor – sometimes utilizing both at the same time.
Fuel consumption (combined test cycle) for the Hyundai TUCSON Hybrid 1.6 litre T-GDi 4WD in l/100 km: 6.6 - 5.2; CO2 emissions (combined test cycle) in g/km: 149 - 140 (WLTP). All WLTP-Values here.
6.6 to 5.2 l/100 km is between 35.6 and 45.2 mpg. That might be what you could realistically expect. It's certainly what I would.
The electric motor is 44.2 kW (60 PS). The combined total with the 1.6 petrol engine is 230 PS. Therefore the petrol engine can deliver 170 PS, which is about right for a modern petrol engine of that capacity. And, I'd suggest, perfectly adequate alone, for an SUV of that sort of size. The usual state of tune for that engine is 150 PS.
Not the 265 hp that you stated, which bemused me. 230 PS is 226 hp. And could maybe do so for 2 minutes total. Before the battery gets charged up again by the ICE engine, and/or some regenerative braking. As for running it on the battery alone, 1.49 kWh isn't going to get you much further than six miles. I can't see how they could credibly claim that you could get 31 miles from it.
Now I may be wrong about the battery size in the one you are considering. For example the Prius plugin has a 4.4 kWh battery, (which weighs 80 kg), and can run it around for 30 miles or so, their figures. That presumes nearly 6.8 miles/kWh. On that basis a 1.5 kWh battery might be good for ten miles, under laboratory conditions.
A hybrid also carries around the ICE engine, fuel tank, plus the electric motor and other drivetrain complexities.
Perhaps yours will have a battery of similar size, rather than the puny 1.49 kWh thing that is what Hyundai seem to say that they have. There doesn't seem to be a lot of point in plugging them in, though a 13A plug could fill 1.5 kWh in 30 minutes, or 4.4 kWh in 1.5 hours. Hence why they don't generally do rapid charging. Plus faffing about with cables (on your driveway), assuming that they were fully discharged, which the hybrids try not to let themselves be, in real driving around.
PHEVs ISTM, are a dead end.
FWIW, the Tesla 3 battery, long range version that my friends drive, weighs 480 kg.
Whereas ten gallons of diesel weighs about 36 kilos, and can get me about 450 miles at fast motorway speeds. My 3.5 tonne 6m long campervan has a 125 litre tank, and has several times done well over 800 miles before the light came on, in insanely hot weather (over 40 C) with the massive aircon running full blast.
And of course a fuel tank diminishes in weight as it runs down, say on average half of that. And you don't need to brim them unless planning a long run. Batteries weigh just the same, whether they are full or empty, and in a hybrid you are committed to lugging around all that extra mass, whether it is put to any useful purpose, in reality.
My Tesla driving chums do note that they have to moderate their driving to get the expected range, on A and M roads. Strangely they can get more range on their hillier cross country drives, where average speeds are lower, and the regenerative braking averages the use out, but that makes sense when you think about it.
So I looked at
Autocar:
Where I read that
The 227bhp full-hybrid improves on these figures significantly, approaching an average of almost 50mpg and emitting 127g/km of CO2
FWIW my old 2.0 140 hp VW diesel can do 50 mpg. and with a chipping could put out 180 hp. with no other mods, but I don't see the point myself. It can do 130 mph as it is, and I have never felt underpowered.