Ioniq (and all Kia/Hyundais) have a far better hybrid set up than Toyota, with the engine switching off at speed and just running on battery where possible - whereas most Toyotas just use the electric motor to give a power boost outside of town speeds.

I presume you mean HJ that superunleaded is 12p cheaper than super diesel, as the difference between standard versions of the fuels is still only about 4p, according to the AA.

Even the cheapest superunleaded (without all the extra nice cleaning additives of the barnded filling stations) is about 4-6p a litre more expensive than RON95, never mind the likes of Shell V-Power SUL, which I find is about 12-15p more expensive than standard UL fuel.

Would the Camry really achieve an mpg boost of that much (10%) under SUL, given it's not a performance car specifically designed to take that fuel rather than 95Ron? Apart from a few reports (often German cars), most people driving ordinary cars (myself included) seem to only achieve a 5% increase in fuel efficiency when using SUL, even when factoring in usage patterns, maintenance and age of the car.

As for the Aurus, I used to get 45mpg out of an old 1982/3 Audi 100 2.2 Petrol; so much for progress!!!

I suspect the old Audi weighs less than the modern (packed with gizmos and loads of safety devices) Auris, plus the more moern car has to deal with a very high bar as regards emissions regs, which reduces the efficiency of the engine - after all, a CAT (amongst other such devices) is an exhaust filter, reducing the flow rate of the exhaust.

The amount of nasty chemicals (whether bad for climate change or to human respiratory health) being emitted by the old Audi is likely to several (even tens of) magnitudes higher than the Auris, even under real world conditions. I also would point out that it's likely that the Audi would have to be serviced every 6k, incur more reliability issues and would also have a shorter lifespan for common parts than the Toyota.

I also know which car I'd want to be in if I had an accident, and it ain't the Audi 100.

RE. hybrid mileage, I have a kia Niro, (same car as Ioniq) 16 month old, 11.000 miles on the clock, doing mixed mileage and using BP Ultimate I am getting 70+ mpg, 2 points, the mpg seems to be better in warm weather ?, and being that I am 75+ I am past the time when I have to race from the light and break hard at the next set! Which seems to be mandatory for German car owners!. You will find driving a Hybrid/Electric means you will change the way you drive.

The car will use less power in the A/C system (unless its consistently well into the high 30s outside) in summer than the heater does in winter, also because the weather is generally sunnier/drier and lighter for longer, so you don't use the lights and wipers as much as well.

My 'old' (13.5yo) Mazda3 1.6 petrol just achieved 44mpg or so on my holiday to the West Country; it only gets about 36mpg in winter (I mainly use it on longer trips on faster-flowing roads, so my car's mpg will be higher than average for that model), which bears out my comments above.

Ironically, hybrid cars often get better mpg on mixed mileage rather than on motorway driving as they can get the benefits of coasting down hills and regenerative braking more than on nicely-flowing motorways where the hybrid battery will discharge quite quickly if used, because it cannot recharge as described, only by sapping power from the ICE engine, which obviously uses fuel.

The 'old' rule that in warmer weather (especially if the car has been sitting in the sun a long time and is very hot), it's more energy efficient to have the windows open to initially purge the hot air inside and to help cool the interior surfaces when the car is being driven at or below 40mph (it will vary depending upon the engine power, laden weight and aerodynamics of the car in question), circumstances permitting (for security and air quality, reasons I wouldn't do so in many built-up areas), of course.

Once you feel you are getting hotter again (once the air cannot cool the interior surfaces much more), then the A/C can be switched on. When it is really hot outside (well over 25degC), especially if the relative humidity is also high (above 60%), then its likely to have to go on earlier because the (possibly very humid) outside air will not give as much comfort.

I also find it can be better for comfort, especially in cars equipped with climate-controlled A/C, to set the desired temperature up 2-3degC in such circumstances for the first 5 minutes or so of use to avoid 'thermal shock' - you'll notice this when entering and leaving an air-conditioned building when the internal temperature is set quite low (say 20-21degC) and the outside temperature (especially in the sun) is in the high 20s and above - the difference in temperature feels uncomfortable for a while until you adjust, which normally takes a few minutes.

In the same vein, I also turn my car's A/C to that same higher temperature as when I set off, or completely off about 3-5 minutes from my destination, and just rely on air coming in via the vents naturally for ventilation, so that I don't get the thermal shock (well, not so much anyway) on getting out of the car.