GBP (United Kingdom Sterling) approximate prices briefly gathered at time of post:
UK Ionity, per kwh-
0.26GBP with 15.15GBP monthly Mercedes Me sub (SUBscription).
0.35GBP with 16.99GBP monthly Ionity direct sub.
0.45GBP with alternative 4.15GBP Mercedes Me monthly sub.
0.69GBP with Ionity directly and no sub.
0.77GBP with Plugshare and no sub.
0.926GBP with Chargemap and no sub (using the well situated Milton Keynes Newport Pagnell as example).
UK BP per kwh-
0.57GBP for the fastest chargers or cheaper for slower chargers or with sub
UK Tesla per kwh-
0.39GBP? to Tesla cars only.
0.50GBP? with 10.99GBP monthly sub.
0.58GBP? "average" though may be higher at the most useful chargers and times!
So, if driving a non-Tesla, Ionity with Mercedes Me cheapest sub is always cheaper than Tesla sub. It is also cheaper compared to Tesla with no sub if charging at least once a month getting a partial charge of 50kwh (as a fraction of the 80kwh full battery capacity in EQC as example). If charging more regularly than monthly, Ionity or Mercedes Me subs will also be even more cheap by comparison with no sub Tesla or sub Tesla.
If driving a Tesla the Tesla chargers will be cheaper than Ionity though an Ionity subscription seems cheaper if getting over about 330kwh worth of charge monthly, which is about 5 partial charges of a Tesla Model S approx 100kwh battery capacity or 7 partial charges of Model Y (75kwh approx battery capacity).
If charging non-Tesla with no sub then Tesla charger might "average" 5GBP cheaper than Ionity for about 50kwh worth of charge however as prices may vary Tesla could still be higher at the most useful locations and times of day compared to Ionity price never varies, and networks other than Ionity will likely be cheaper such as BP. And Mercedes new UK EQ cars have charging port, on different place to Tesla like most non-Tesla, on driver's back right hand side compared Tesla on driver's left back side, so Tesla chargers could be awkward or useless in cases as Tesla warns to not straddle parking bays.
I do most of my charging at home (South West) and most of my trips are that direction. I have used the only IONITY charging station in the SW, Columpton services on the M5, Also used one on the M25 when I went to London - both great options for me. Gridserve are also fast & reliable.
Overall it’s only once or twice per month, usually with a different provider, so a subscription is not worth it for me for any provider.
I welcome opening up the Tesla Superchargers - it gives me other options - but there is only one near me in Cardiff at the moment 😂
Yes, if only charging less than 5 times yearly at Ionity or Tesla chargers there is no point in a sub. For EQ drivers there is even less reason for Tesla subscription, except fast charging about 50 times yearly and Ionity is too faraway. I have highlighted in green some of the best value for each annual charging pattern in the attached.
Another perspective is if possible to subscribe for a month then unsubscribe, it is better to get Mercedes Me even for one tiny charge in UK, compared to Tesla subscription multiple charges would be needed to make it cheaper than not being subscribed (over 140kwh total). The last time I tried this subscribe and unsubscribe method there was a lot of admin to make it happen though; it might be better now, not sure.