Yep people want petrol cars when it comes to sports cars, especially "purist" petrol cars.
Lower down the market they are all holding their value now pretty much. Classics like the S2000 and s1/s2 Elise are going UP. Even my gt86 still has half of it's value after 5.5 years which is nuts.
They will continue to do so, days of picking up an E46 M3 for under 5k generally don't exist any more unless its a terrible example. But on the flip side M3 CSL which were fetching over 60k, are now trading between 40-50k, there is certainly a correction happening on the upper end.
But yeah the lower end are certainly still holding value and many are indeed increasing.
Jon told me earlier you can now get an MY17 GTR for under 60k, bargain that!