I bought the same 12GB/12 month one from 3 that is advertised in Jim's link. I bought another one last month when the first one ran out of data. It lasted nearly the full 12 months so I know 12GB is the right amount for me. I bought from Amazon last year and eBay this year but same thing and similar price. Current: Volvo XC90 T8 Inscription Pro PHEV with some optionals on top
Gone: MY16 RRS2 3.0 SDV6 Autobiography Dynamic, Carpathian Grey & Santorini Black Sliding Pano/Ebony & Ivory 2 Tone
Gone: MY13 RRS 3.0 SDV6 HSE Black Edition, Orkney Grey/Ivory
Gone: MY09 RRS 2.7 TDV6 HSE, Santorini Black/Almond

I also need to get a sim for my new MY17.5 RRS, arriving on the 1st Sept.

Looking at the PAYG route as suggested above, but does anyone actually know how much data is used in the new ICTP on a monthly basis? Don't really want to run out if i go for a 2GB per month one.

I'm not interested in the "in car wifi", didn't even bother with the sim in my MY16.5, but i see that it uses data for mapping and other useful features in the new MY. Now
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2022 SVR
2021 Bentley Continental GT
2020 Defender 110
2022 Defender 90 V8
Plus 16 other toys!

I've got a 750 MB/month SIM which came free with another service, and that's proved sufficient for me doing similar things to what you intend. The bigger problem for me is finding a 3G signal (there's no 4G facility in the car!) and having to re-set the mobile data to get it to search for the SIM again on the occasions it just stops. Once you've downloaded a map, it saves it, so obviously the more new places you go the more data you would use, but it seems to acquire a map with very little data consumption anyway. Last time I looked, iD (a Carphone Warehouse subsidiary) did the best SIM deals for this purpose.

Can you just pair to mobile to download maps through the phones data? Or can you not connect to
Home wifi and download that way?

I have a My17 to collect on the 8th September

Don't want to use as wifi hotspot so what would I need the sim data for?

I'm not aware of any way of downloading Google satellite maps other than with a SIM, but, as I said above, once downloaded they are stored. The satellite mapping is very effective and I use it all the time, even when I'm not using navigation. You also need the SIM for traffic updates.

'In Control Pro' also needs a SIM, although I've never managed to find or use any of its claimed facilities such as Sharing ETA, Seamless Journey Arrival/Parking information/360 degree view, Simplified Daily Routine/Fuel required for planned route/fuel prices, etc. These are all fulsomely described in the brochure but don't appear to exist in reality. (It does appear to list searched-for fuel stations in price order, but without actual prices). Nevertheless, the cost of a SIM is so trivial compared with the cost of owning and running the car that you may as well have one in my opinion. (The bigger bugbear is it's tendency to turn itself off periodically).

EE have an offer on for a 30Gb data sim on a rolling contract at half price, down from £30 per month to £15 per month. Expires 13th Aug.
I've ordered one, which was sent 2nd Class by Royal Mail on Thursday, but not arrived as yet.

Just ordered one from Three online through mymemory

12gb valid for 12 months for £24.99 with free delivery